What I would suggest for the future is contact your bank and ask them if you can link your account activity to your cellphone...that way you would immediately see if it was swapped twice because the amount would then be subtracted twice from your account and you would get 2 sms ,s to your cellphone confirming that...We in SA can do that so I am sure it is possible in your country..In general I think it is a good idea because any activity on your account gets sent to your mobile..be it deposit, debit orders etc..

You have instant prove and can confront these people there on the spot

cheers
vanman