A William Hill customer suffered a heart attack days after finding out his £285,000 ‘jackpot’ was a ‘glitch’. 

John Riding, 76, was one of many customers of the gambling firm who thought they had won prize money – only for it be removed from their account following a malfunction, it is understood. 

Now, William Hill and 888 Casino – two of the UK’s largest betting brands and both owned by Evoke – could face a group action from impacted customers. 

The glitch is understood to have stemmed from the Jackpot Drop Pool, a mechanism used by Evoke. 

Mr Riding, from Burnley, was rushed to hospital less than two weeks after his six-figure prize turned out to be a mistake. 

His son Adam told The Mirror: ‘One minute he thought he’d won £285,000. It was like all his worries were finally over, and the next it was just taken away without any proper explanation.

‘The shock of that has been unbearable. It’s not just about the money, it’s the way it’s been handled. It feels like a real injustice, and the stress of it has had a serious impact on his health.’    

Mr Burnley is said to still be recovering in hospital after his heart attack. 

Some customers reportedly made ‘major life decisions’ after thinking they had won up to a million pounds, only to find out their victory was a malfunction. 

Paul Kanolik, from Ellis Jones Solicitors, said around 50 people had been in contact with the firm claiming they had fallen victim to the error, although it is unknown how many people have been affected overall. 

Postman Steven Harvey, from Dunstable, thought he could finally buy a property, only for his £330,000 prize money to be removed from his account, leaving him ‘crushed’. 

Mr Kanolik said some customers had already relied on their winnings to make serious financial decisions. 

A spokesperson for William Hill, from Evoke, said: ‘During a routine review of platform activity, we identified an issue affecting the Jackpot Drop game which temporarily resulted in incorrect sums being credited to players’ balances and withdrawals being processed incorrectly.

‘Whilst we quickly identified and resolved this issue, for a short period of time funds were erroneously credited to some customer accounts that were not correctly generated through valid or properly functioning gameplay.

‘We have contacted relevant customers to clarify the issue and are in the process of retrieving the funds in line with our standard terms and conditions. 

‘We have been grateful for our customers’ understanding on this matter and apologise for the inconvenience caused.’ 

In previous years, cases have seen betting giants made to honour payouts to customers. 

Andrew Green, 54, was handed £1.7million by the High Court after he was prevented from withdrawing his winnings from the Betfred app due to an alleged system glitch.  He described the ordeal as ‘torture’.