Extremely Poor Service

HI i have a contract with MTN and took out a LG G4 phone. The phone has been giving me endless problem when do a software update it just freezes and just reboots all the time.I took my phone in for a repair a few months ago because it was just freezing and rebooting all the time.MTN Repair centre then replaced the motherboard and gave me the phone back.Firstly i lost all my stuff on the phone and it became a real inconvenience .On the 26th of August my LG G4 started giving problems again it was just rebooting and just didnt want to come back on. I then took it to the MTN store where i took out the contract and the gentleman said he will sent it in on the Monday which will be 29th of August.Hi have been calling the MTN repair centre from the 3rd week and was told thet awaiting spares for the phone. I then called again on the 19th of september and was still told MTN is awaiting spares and should call again on the friday which is the 23rd.Hi then called the friday and was still told that MTN is still awaiting spares.I am honestly fed up with the service that i am receiving from MTN as a customer and feel the service is extremely poor.the gentlemen on the other end of the just kept quiet and not responding at all to my conversation and spent over 20mins with no satisfaction.If this is the service we as customers received its pathetic and i feel they should cancel my contract with immediate effect and keep the phone.MTN does not send any communication to keep the custoemr updated on the progress of the phone which is totally unacceptable.