I want my money back. I'M ****MED

I called in July to change my package as I was paying for high speed but the highest speed I would get was 10. I was called and promised a technician would come but nothing happened come August I called to cancel my subscription and I was then sent an email that my cancelation request was received ref number:*** Then I received another email on the 16 August after speaking to an agent that my cancelation has been scheduled. At the end of August, I made a payment. To my surprise, at the end of September rain debited my account and on Facebook, I am being told that I canceled in September how... When I September I did not even use your device. I have been calling, and sending complaints on Facebook I am not getting help. The router device was sent to them but no refund till today. They failed to deactivate my SIM-CARD end of August and billed me for September which I felt ****MED. They charged me because they failed to do their job on time. Who's responsible for SIM-CARD deactivation?? I want my money back, please.