Truworths birch acres mall

It hasn't been a week since I wrote a review here about the cellphone I bought at Truworths Birch Acres and had to return it because it was faulty and not charging. The phone was dispatched to Mtn and now they are saying it's not charging due to liquid damage /corrosion and they can't fix it because it's something not covered by the warranty. I'm expected to pay for the repairs which is R800 something plus I'm still paying for the phone which I took on a account.

How is this fair? I was also told to pay a courier fee? Someone please help me because I'm sick and tired of Truworths I just want my refund back they must keep they're faulty phone!!! This is a phone I bought on the 15th of October. I am going to escalate this to Ombudsman. I'm sick and tired