Wrong debit date

This company is the worst, no matter how desperate you are never ever take a contract with these people. I took a cell phone contract with MTN on the 15th of September 2024. I requested the salesperson to set my debit date for the 22nd of every month since I get paid on that date. In October I received an invoice on the 12th by an SMS reminding me that I’m advised to make a payment on the 15th. Upon receiving the SMS I tried to get in touch with to resolve the payment date issue through Facebook and they indicated that the debit order will go off on the 22nd from November. But instead, it went off on the 15th of November and it bounced. On the 22nd of November I went to MTN at Mall of the North and requested them again to change my debit date to 22nd of which the sales consultant told me that the debit order date on the system is the 22nd.

To this date MTN keeps debiting me on 15th. This has affected my credit records, and my livelihood as lenders are reluctant to give me credit because of MTN's the debit order that is unsuccessful every time on the 15th as I would not have been paid on that date.