Telekom Samsung Note 20 ultra battery lifespan less than 5hrs and overheating.

I bought a Samsung Note 20 ultra at Telekom centurion mall. Its battery last for less than 5hrs without playing games or musing. It overheats. When I took it back there were other ppl complaining about the note 20 overheating problem. It is on contract paying debits but don't have a cellphone. Lutendo the manager says they will fix it and I said it is still new why fixing it not giving me a new one she refused to give me a new fone she said they will fix that one. A new cell phone must be new not have to be fixed within few day of purchase.