MTN deducting for service not rendered

I had a contract with MTN for the router but it happens that there is no signal in my area. I called customer care and they said I must take it back to any mtn shop which I did, in August I took it back to mtn Richard’s bay

I have been sending messages telling them to stop their deductions for the router that is not there and was hardly used.

They still have sent a message that they will deduct this month, since July they are deducting 295 but in July it was double deduction

I want my money back and mtn to stop this debit order

Zamandla Vilakazi ***