Cellphone was send back 3 times

Hi Peter my name is soewayda Rogers I bought myself a cellphone by Mr price some time last year I bought myself a hisense something in my price range and something I could afford however after 6months the phone just went blank wouldnt go pass the hisense logo took it in it was send off too repair as I was told it was a signal problem. I waited and waited then I was told I can come and collect my phone this was Mr price in vangate mall no communication whatsover I asked if I couldn't change that one for another I was told no! It's not part of the policy. I bought it on my account the network provider was Mtn I received a new one same problem this happened three times after I received the last one I went back to the store spoke a really nice girl told her I don't want the phone anymore amd I'd like something else with another network seeing Mtn was apparently the problem I dropped off the phone on the 15th Feb 2023 and was told that they will connect me it's the 20th of July 2023 and still nothing I haven't heard from and paid for a cell phone I can't use what do I do