No success with VRS billing problem complaints

Up to two months ago everything was fine. After that they said the debit orders for the purchase of units and the levy wasn't paid by my bank because of a code 50 error. Apparently they wanted to debit my credit card all of a sudden and not my cheque account as in the past. Apparently, the bank doesn't allow debit orders on credit cards. In any case, I never gave them permission to deduct the fees from my credit card account. I sent them two or three previous emails giving my correct bank details and have spoken to at least two consultants to no avail. Lo and behold, today I received another email saying I didn't give them my correct credit card details. I rep**** that I'm definitely not going to give them those details because they have my correct cheque account details. I'm getting concerned - For two months now they haven't deducted the instalments as they did in the past. Should I cancel the debit orders and rather pay the instalments electronically in future, because something just isn't right with VRS.