MRPMobile - NEVER again!!

I was contacted via phone to sell me a mobile and contract. I received the mobile but found the reception and service to be non-existant. I complain to no avail. After about 2 months, the phone stopped working and on enquiry, i found that it would be more expensive to repair it than it is actually worth and nobody wanted to repair this low-quality device. I had no choice but to pay the 2 year contract. When it expired i advise via the website that I wanted to end. No response. I went to Tygervalley Mr price and Cape Gate Mr Price, called the call centre and they simply referred me back to emails. I resend an email directly from my mailing account to '***' as advise instore, rather than the website with reference and all to indicate this contract ended March 2020 and the phone, therefore, has been paid and the service should be suspended. NOT only dit they keep charging, but the amount also increased!!!! It seems impossible to cancel this without changing my bank?!