UNLESS phone bad customer service MTN

Good day

hope you are well, i bought 2 phones from you guys Hauwei Phones and the Hauwei Nova 10s battery started swelling and cracked the glass at the back and now the phone fails to charge , these phones arent a year old and when i spoke to the gentlemen from your MTN trade route store he said that there is noting you can do which i feel is nonsense as this is not self inflicted and this phone is under warranty. i mean i cannot be paying so much money for a device thats not working and has a failure to do something i didnt do.