your card is suspended until the final outcome decision,this takes around one month to complete even longer if the police are investigating because the club will wait for their report, so in the one months wait your likely to miss say 3 games then if no club action your card will be re activated, no refund whatsoever for the missed games, on the legal side a 100% win case if you took MCFC to County Court to recover losses, we are all at the end of the day just customers who are protected by the consumer rights
'is it legal for them to keep your money' probably not if they cant prove you offended but most other businesses other than football would refund you, if it was Home bargains you could simply stop shopping there and go to wlko however the problem with football is there is only one MCFC and the customer is highly unlikely to go to Manchester United.
just to add my lad got his S/T stopped at the last home game of the seasson against spurs a few years back, he was arrested by the police at his seat and taken to the station, it took the police 3 months to decide either to charge him or not (he was placed on bail),the result some 3 months later was no charge insuficient evidence,thankfully it was the last game of the season if it was the first he would have missed up to 8/9 games,,the lad started going to city when he was 3 years old and never missed a home game up until aged 17 when this incident took place,since then he has never set foot in the place and will never again in the future