Contractual misinformation and failure to resolve complaints

MTN consultants offered me a data contract which I was delighted for. However, they were not truthful about the collection date of the debit order. The consultant told me that I could pick any date for the debit order mandate but it turns out that the company has a select number of days they collect on, they did not make me aware of this at all and to my surprise, the debit order mandate would go off on a different date than the one I selected. I wrote to MTN to ask them to investigate why the consultant gave me incorrect information and they have not responded to me in almost a month although they promised a 72-hour response period. I also asked them to then change the collection date which they said would only be available from the following month, they have now cut off my service for alleged failure to make a payment although the fault is on their side with the misinformation I was provided with from the beginning of the contractual agreement.