poor service, poor network

Got a phone on the 3rd October 2020. I have been having endless problems with the Network. I have been in contact with MTN all the time. I now want to return the phone and cancel the contract. The customer service consult advised that I need to return the phone to the store. The store advised that I will be charged a cancellation fee. I took a contract for 2300 a month and was debited R3075 this month and now I am advised that its a prorated amount. Why do I need to pay for a service that I do not benefit from. This is the worst network ever. Can I have this contract cancelled and return the device.