Terrible service samsung care centre kzn

I took out a contract with mtn last year December it was an upgrade on an s6 edge I have no issues ever taking my phone in to samsung repair centre However this contract was done over the phone. Mtn has sent me the imei no on my contract together with a letter from them stating the confirmation and samsung is still awaiting for authorisation and feedback with their head office it is clear the phone is on contract with mtn so I cannot understand why samsung is just delaying the matter .it has been 3 days and still no feedback the service is just terrible Who can get involved and assist with this samsung surely has a record of their phones why is the customer being punished.