MTN can’t stick to terms and conditions.

I was offered n MTNa home Wi-Fi package through Mondor telephonically. I accepted it and was told if I return it within the 10 day-cool off period, there will be no cancellation charges. I called MTN to cancel the service and returned the router to an MTN shop close to me as per instructions on day 7. MTN went on to bill me for the month including pro-rata. I called them and they refunded me. The next month they deducted money from my account including cancellation fees….. a staggering amount over R4000. I have been trying to get my money back from September 2022 to date. They just say we are investigating, we will call to give you feedback each time I make a follow up. Its frustrating!