Unhappy Customer

I was in need of fibre and I went online to enquire with Mtn on my search I came across Supersonic I app**** online submitted my banking details and everything a few days later I received a text saying that I should expect a call from a certain cellphone number to confirm if I'd be available so that they can bring the equipment and set it up. I waited and waited for a call but nothing. I've never ever received a service from them nor did I receive the equipment. I sent them emails and I tried to call them a number of times but to no avail. Now they continue to send me invoices for something that I don't even have. They attempted to charge the monthly payment from my account but with no luck. Please assist me as I don't know what to do anymore. I don't want to be listed on the credit bereau for nothing. Unhappy customer!