I need someone that is Competent that can call me regarding this matter

This is by far the worse Network ever. I have been with MTN for years. I currently have a contract with MTN which is expiring next year July. I visited the store on the 19 June 2019 because the speaker of my IPhone 7 is not working. After 4 weeks I went back to the store to enquire about my phone and they gave my phone saying that my phone is fixed. I arrived home and the speaker was still not working. I went back to the same store at Brooklyn mall very upset and the Staff did not know what to do. I decided to go to a different MTN store still at Brooklyn mall at the Design Square I visited The store on the 23 July 2019 explaining My story again. I was assited by Rhinus who was very professional that took my phone saying He will book it in for repairs. Today is the 1st of October I haven't received my phone as yet No one at MTN has contacted me to provide me feedback. I took it upon myself to contact the Repair Store I found the number on my Invoice. I was told I need to pay R4700 because my contact has expired how is that possible I took out the Phone last year July 2018. I was told that My phone cannot be fixed due to that amount I need to pay. My question is if my phone is not fixed what is it doing at the Repairs still, I Have already requested for My iPhone to be send back. I am currently Unemployed I cannot stress this much. I really need help regarding this matter I am depended on that phone. What is the reason that I need to pay that amount and what is the reason that my phone is still being kept at The Repairs if they are not willing to fix it