No help from Mtn

Im heartbroken about mtn,i have been a customer with them for about 15 years.i got a call to say im due for an upgrade and i said i dont want to take a phone and the person said i can just take a sim only and i agreed.my bill went so high and i called to check why. Was told by mtn to call the outsource company as they did my upgrade.their number not going through .i emailed them twice no answer. Was referred to speak to sales and sales cant help me and referred to speak to one different departments .they charged early termination fee and never asked to terminate early. Went to mtn shop and they dont even see what they did on the system.by bill keeps going extremely high.i dont know what to do.there is no answers. They now blocked my number. Im in pain .no one can give answers. I dont want this company anymore. No one can explain what happened to my account or fix it