Faulty phone

I recently updated my contract and started using my new phone on the 25th of November reason being it didnt come with a charger and i had to buy a charger , ok so from day 1 i noticed that this phone needs to be charged atleast 4 times a day mind you its a new phone SAMSUNG Z Flip , so i call vodacome and they say 14 days have passed so they cant change the phone for me and i should go to a vodacom outlet , when i go to the outlet they say i should go to SAMSUNG and diagnose the phone than repairs will take 3 weeks . what should i use during those 3 weeks , i love my phone all i want is for them to give me a phone thats not faulty why cant they change it for me beacuse i cant keep a phone constantly in the charger for the next 3 year im sure its going to get worse.