I pay them but they hand over my account

I have a contract with them ***. I once complaint about them debiting some months and some they dont debit. As in today they have not debited when i go to store they say my account have been handed over to external collectors as to why i dont know because they have confirme that every months im paying them and my account was infront with one month. I called them mid month of january to activate my line but to my suprise today they say i fail to hourner my arrangement which was suppose to be manual payment. I dont know why manual payment because all this time i have been paying by debit order. Now they dont want to reverse their mistake of handing over my account when i was paying them and not even skipping one month. I went today to ask why there is no debit order this month then i got this suprise. I wish them to bring back my account and do debit order as ussual.