Phone quality and bad service

I have an issue with mtn bad service i took out a contract with MTN online in December 2021 i received my phone towards the end of December 2021 however am experiencing issue's with this phone Samsung Galaxy A32 it keeps popping up an alert saying the phone is over heated I've switched off this phone numerous times and this alert keeps popping up i can't even do anything with this phone due to this alert i called MTN was informed to go to any MTN store which i did today however when i arrive at the store I waited for hour's before being assisted and was told it just an alert how possible can that be!!? Then after am told to produce an invoice as they can't retrieve it on their system this phone is on contract a monthly debit order goes of on a monthly basis they know where to get my money but in terms of assisting with the issue at hand no one is stepping in am being sent from pillar to post without any assistance wasting my time get my invoice from your system's and fix this damn phone i pay every month for this device do the right thing!!!