Billing issues and incorrect debit order dates.

I have a Nedbank loan via Cash build, i called in last year to change my debit order date and when the Agent asked me to confirm my bank details, she said the acc no on their side is not the same as mine and she corrected it. But a few weeks after i started getting calls that my acc is in arrears while the debit order went off every month, when i followed up i was told that payments were reversed to my account, but i had no knowledge of that and didn't receive any of that money instead after that i was debited double for 2 or 3 months and on top of that no dates were followed as arranged. My account was debited anytime when i get money deposited into my account, that is still happening as the last time was a week ago which is 2 weeks before my pay date. I've been to the Loan centre in Midrand but still my issue has not been resolved and no one is giving me a straight answer about how incorrect banking details were loaded on their side whereas i was debited monthly and to which account was the money reversed which i had to pay double for? Please sort this out as the \Anytime debit"is a huge inconvience to my budget. I requested to be debited (1st day of the month not ANYTIME."""