WHO SAID CHANGE MY DEBIT ORDER DATE???!!!?

January 2020 called to cancel my contract with Vodacom( lady said my last payment would be in February) I relax thinking everything is sorted then boom March I get messages saying I haven't been making payments(mind you its a debit order) I don't pay mind to it cause surely its a mistake. April comes along and the same message come through and I'm getting worried now and start making calls only to find out after I have talked to almost all the consultants that were working that day that THEY CHANGED MY DEBIT ORDER DAY without my consent and now their debit attempts have been unsuccessful because the day they choose my account is usually and now I have incurred charges because of them. Called and I was given hope that it will be sorted and that they will activate and change my debit order date but still they didn't deduct and I haven't received any reference number that I was promised to get and I'm still waiting for the recorded call I made were I said I want to change my debit order date....NOTHING from vodacom and I will not pay for anything until I get an explanation of who gave them the right to change my debit order and who will pay for the extra charges?!

Very annoyed with this company and I actually no problems with them with my other contracts but now they just irritating and I want nothing more tondo with them, can't even cancel my current line because of the mess THAT THEY CREATED THEMSELVES!!!!