Inredible Connection Eastgate- Poor Service

I bought a Samsung A30s on credit from Incredible Connection Eastgate mall last year November, the phone has been restarting itself and sometimes I wake up with a super hot phone, not sure if it is a battery problem or what. I went to the Eastgate branch to ask for a tax invoice since I bought the phone from them, to take the phone for a repair at Samsung, I have been given the run around, no one has called me back to advise and I have insurance for my phone but no assistance. All I want to know is how long will I use a phone that restarts itself for no reason while the staff at Eastgate do not want to help!