As a convicted fraudster responsible for swindling investors out of more than £100m, the shamed US stockbroker Jordan Belfort is an unlikely role model for staff handling the delicate process of selling funerals.

But that did not stop a firm that traded thousands of pounds’ worth of pre-paid plans for elderly people each month from installing a cardboard cutout of Leonardo DiCaprio as the notorious lead character in The Wolf of Wall Street in its call centre. The organisation, they say, had a culture of putting sales first.

The DiCaprio figure was not the only surprising feature of Prosperous Life’s office. Whistleblowers claim that when employees managed to close a deal, managers would rain down fake notes of cash on to them using a “money gun”. On other occasions, they said that sales staff would be rewarded by being invited to pluck £5 or £10 notes from washing lines running along the ceiling. Loud music was common, as were games of limbo and egg-and-spoon races.

And the high-pressure sales approach described by former employees was embedded in the language used by call-centre workers, who, texts received by the whistleblowers show, referred to themselves as “lions” and customers as “gazelles” to be hunted.

Those descriptions were reinforced by management, which the whistleblowers say plastered the office walls with pictures of the wild cats and sent out motivational WhatsApp messages to staff referencing the animals.

In a bid to gee up his troops, messages seen by the Guardian show, one manager wrote : “Right team we have a great day ahead of us, down to us to make it great … going to be loads [of] gazelles knocking around in the grasslands again today so when we get starting you need to have claws out, win the fight and bringing them back home to the pack!

“Remember ‘gazelle will never say just eat me’ we have to hunt and it starts at 09.00!” He added five lion emojis.

On another occasion, the firm’s co-director, James Murtagh, sent employees a Wolf of Wall street gif at 6.54am before a shift, featuring characters in the film beating their chests.

A whistleblower recalls how the company’s other director, Ian Blackhurst, gave a speech to staff and then put a “motivational” video on for them to watch. “He was explaining how the gazelles runs away from things and the lions take what they want,” they said.

“The actual video itself was a very motivating thing but as soon as Ian started talking it was like: ‘These people on the phones are the gazelles, you are the lions’.

“That was an ongoing thing. It just made me feel uncomfortable. These are old people and we’re talking about being lions. It just didn’t make sense to see these people like that but it was always an ongoing thing on the group [WhatsApp] chat. There’d be lion faces every morning.”

According to one whistleblower, staff were told: “If the customer hangs up then we win but if we hang up, they win.” On one occasion, a manager even encouraged a salesperson to watch The Wolf of Wall Street for inspiration.

Scores of online complaints detail the impact the company has had on potential customers. On one forum featuring more than 70 comments about the company, one woman wrote: “They are harassing. They ignore emails and instructions not to ring or contact. This is invasion of privacy and it’s harassment.”

A separate consumer review website, Trustpilot, features mostly positive reviews – but there are are dozens in which people have rated the firm one-star and give a troubling view of its sales tactics.

In August one person wrote: “Every night I explained that I wasn’t interested and asked them to delete my details – which they said they would – but they keep on calling night after night after night.” The customer said they had referred the company to the Information Commissioner’s Office (ICO).

In October a man wrote: “I made a enquiry with this company over a week ago, and have had 57 calls from various numbers regarding my enquiry … they continue to call and won’t remove my details from the system. This company tried high pressure tactics 1st time round and still pester me now.”

ICO guidance says that marketing calls to customers should “stop within 28 days of receiving the objection” and sooner if possible.

A spokesperson for the company said it did not cold call customers and that all of its contacts came via an initial inquiry form filled in by customers and potential customers on which it received 4,000 such queries each week. The firm said it had “demonstrated to the ICO that all potential customers have provided contact information and requested to be contacted about the funeral plans”.

The company said it showed motivational training videos and self-development clips to “incentivise” staff, including one in which a “world-renowned speaker” referenced lions and gazelles. The firm said the link to DiCaprio’s character was used in compliance training as an example of “one of the most notorious breaches of compliance” and that it wanted to “show the difference between right and wrong”. It also said the cutout was in the office as part of a sales promotion in which staff could win a trip to New York. The promotion also featured a cutout of Donald Trump.

One whistleblower, who feels most staff were pushed into dubious practices, reflected: “The sale was the be-all and end-all. They didn’t mind if they pissed off 10 people to get that sale, they were happy to do it.”