Bad service

I signed a contract for 2 years at MTN somerset west on a Sony XA2 Ultra in 2018 June. 2019 June I had problems with touch screen booked it in for repairs at Swellendam and when I received it I had problems with connecting to a network.since then the phone was up and down for repairs from Swellendam to SSS cellular. End of the day the phone had 3 different motherboards. I went to Somerset west branch where I took out the contract and was informed that they cannot give me a new phone because I handed it in at Swellendam that is actually a franchise. The phone is still having problems. But why did they not mention anything about " for any repairs I must bring it to the store where I signed the contract." Swellendam is 170km from somerset west. The different IMEI NO's are IMEI *** IMEI *** IMEI *** i am paying for a contract of 2 years but only had the benefit of the phone for a year.