MTN Selling under False Pretenses

They migrated me under false pretenses, a few days after I found out about it, I immediately canceled it. They are still deducting money from my bank account. After plenty of emails, and a phone call they didn't cancel it, and they have rep**** in an email that they have investigated it, and the fault was on their side. This is now 3 months later and they keep saying it was cancelled, but when it is time to pay my monthly account, they deduct again more than my original account. This is how they treat a customer of almost 20 years