LONDON, England (CNN) -- A compulsive gambler is suing a betting chain for losses of $4m because he was allowed to place bets after he asked to be barred.
Greyhound trainer Graham Calvert, 28, from Tyne and Wear, north east England, wants William Hill bookmakers to pay back the money on the grounds they failed in their duty of care.
Mr Calvert has gambled more than $14 million on football, golf and horse racing in an 18-month spree beginning in August 2005.
He once lost nearly $700,000 - at that time the biggest bet in golf history - after backing United States to win the 2006 Ryder Cup.
Mr Calvert telephoned William Hill in June 2006 to ask them to close his account after he realized he had a gambling problem.
He says he was offered a 'self-exclusion' policy where he would be prevented from placing any bets for a six month period.
However, two months later he was able to open another account with the bookmakers, one of the largest in England. He went on to place several bets, including the one for the Ryder Cup.
Mr Calvert is now heavily in debt and says his life is in ruins. His marriage collapsed after his wife left him taking their two young children with her.
He is suing the bookmaker for the $4 million he lost after he asked to be barred.
Speaking to the Northern Echo newspaper after his lawyer issued the writ against William Hill, he said: "I was one of the top fifteen greyhound trainers in the country. "My family has been in this business for generations. But now I've lost everything.
"I think it was irresponsible of William Hill exploit me the way they did. It has ruined my life. If I'd known I had the problem and didn't do anything about it, I would see myself as being 100 per cent responsible.
"The fact is that I did try to go through the right procedures and I was let down."
Tiejha Smyth, Mr Calvert's solicitor, said in a statement: "He was allowed to continue gambling after William Hill agreed he should be self excluded. They should be held legally responsible."
William Hill contests the allegations, arguing that customers place bets of their own choice.
The case is due to begin at the High Court next week. E-mail to a friend