Bad service at istore

I'm very upset at the service I'm receiving from istore Midlands mall. Ive sent numerous communications and everytime i go there they tell me the same thing everytime. "We're fast tracking the matter" but still the matter hasn't been dealt with.

On the 26th of August I purchased a pre owned space Grey iPhone 8. On the 16th of September it just seized working and it wouldn't turn on. I sent it back to the Midlands store and I required a full refund as I needed to urgently get another phone and I just didn't trust the brand anymore because how can a phone just die within a few weeks of purchase. The phone was sent for repairs in Joburg and there was a delay because I couldn't switch off "find my phone" from my end but i eventually managed to do it.

On the 8th of October I was told that the phone credit will be in my account via EFT in 7 days. Later I was told it was actually 21 working days. I've been going to the store every second day to find out what the delay was and unfortunately I've just been getting the run around. It's been 29 working days now and still the monies have not been sent. Another thing, I was told a 20% deduction will be made because the phone had a scratch, now when I purchased the device it did have a small scratch on the corner but I over-looked it because it was a previously owned device, now I don't understand why I'm being charged for that scratch. HOW IS THAT MY FAULT. I'm truly appalled by all of this and It's so unfortunate that I'm having the worst experience ever with such a big world renowned brand. Please assist, and they must send me my FULL REFUND ASAP!!!! I just want there 30 minutes ago and I'm hearing the same story again.