UPGRADE PHONE FAULTY - NOBODY CAN ASSIST ME - REMEMBER THE ACT

I received my upgraded phone last week, Samsung Galaxy A12. The phone takes a full day to charge on a port and only properly charges on the electric point. I am unable to use the phone whilst it is charging as it overheats extensively. 4 calls later today I have not had any joy with a replacement. I have been told that it should be repaired (NO, it's a new phone - replace it). And have been consistently transferred to other departments, AFTER having to each time answer the security questions. Once they transferred me to a number which apparently doesn't exist. I've been told to remove the battery for a time and never charge on a port. So what happens when I'm using GPS on long distance calls? Please address the query or I will stop the debit order. I