Online gambling firms may have crossed a line by effectively cheating punters out of winnings they expected to receive, according to a regulator. The Competition and Markets Authority (CMA) said it was investigating if companies were acting fairly, particularly through their use of promotions – such as free bets – amid allegations complex terms and conditions or mistakes were being cited for cutting winnings. Other concerns included players being unable to withdraw deposits, and any winnings, when they want to close accounts and short time limits for submitting complaints. The regulator said it wanted punters to submit any evidence of…