Guarantee not honored

On the 20th of August we took my son's phone in for repairs at Ackermans, the battery swelled up. The phone is still under guarantee. I expected no trouble. Instead, I received an SMS: Hi THABANG ! A payment of R334 is required to repair your Mobicel device. NB A rejection fee of R250 is applicable. SMS 1 to accept and 2 to reject.

I don't understand, why should I pay for damages we weren't responsible for? Battery damage is a manufacturer issue. So after multiple trips back to the store the manager explained that they're requesting a payment because the screen cracked due to the pressure of the battery swelling up, physical damage is covered in the guarantee. But we didn't break the screen??

It's fine, if they're not going to fix the phone why do I have to pay to get it back?? What exactly am I paying for? I refuse to pay for nothing. They haven't helped me or fixed the phone regardless of the guarantee so why should I pay to get back a still damaged phone??

Granted the manager was helpful but because he doesn't deal with cellphone repairs it is out of his hands. I jus want the phone back & I'll see what I'll do.