Unhappy and frustrated by MTN!

Mtn SA has been giving me problems since November 2024. I asked them to do one simple thing for me, to change my debit order date from month end to the 15th of each month. Instead, they continued to debit my account both on month end and the 15th, meaning they are taking my money twice and worse of all, if the debit order bounces, they block my line such that I'm not contactable or can't make any calls to anyone. This is so frustrating to say the least, so so annoying, the back and forth they have put me through, is totally unacceptable!!!