BILLING WITH NO SERVICE PROVIDED

I have a contract with Home Could and my connection was cut off in April. In contacting them I was told its technical problems on their side which led to my sim card being replaced but never reconnected. Since then I have not been assisted but every month I receive an invoice. I have called and send emails seeking clarity but to date there has not been any feedback and unfortunately, every month they still attempt to deduct money from my account whereas I am not receiving any services. This is going to affect my credit record badly and I do not know what to do anymore to reach them. All the customer lines that I call no body picks up. Its either they will answer and keep me on hold without transferring me to the relevant department until I drop the call. Please help