Incompetence overload!

I AM SO FURIOUS RIGHT NOW!!! I ACCIDENTLY TRANSFERRED MONEY INTO MY PERSONAL LOAN ACC INSTEAD OF MY FLEXI SAVINGS ACC.I LET THEM REVERSE IT,WITH MY MONTHLY DEBIT ORDER STILL IN PLACE. NOW ALL OF A SUDDEN THEY TELL ME I AM IN ARREARS?????AND HAS FREEZED ALL MY ACCOUNTS!!!THIS IS UNACCEPTABLE!!!