Service not rendered

I have a contract with MTN for two lines, the devices were Hauwei P7. The one phone had cracked the screen took it in for repairs i was told that the phone could not be fixed so it was declared beyond economical repair, so they gave me a new phone. Now, the other phone fell and cracked at the back and it affected the screen i contacted MTN to book the phone for repairs, i filled in forms sent them through and then i received a call that i should take the phone to a WE FIX shop then i took it to The Glen WE FIX shop all this happened in August. They fixed the front screen bt the back cover was still broken, i took it back in they fixed the back cover after they had to order parts that on its own took them two weeks then the it fixed.When using the device i noticed that the vibration is not working and the speakers were scratchy and when viewing pictures the screen turned red. I took the phone back in they said they fixed but the problems were still there i took it back in early October 2017 when i went to check if it is done they told me they fixed the vibration, they told me they ordered a part for a speaker from DUBAI... to this day i am still waiting the last thing they said was that there is a problem at customs so the part was not released...i really i don't know what to say or do please help actually i do not want the phone anymore because it means i am still gonna have problems... please help