I’m Buyisiwe XWAYI from Port Elizabeth

I Took My Car to Meritime Motors Port Elizabeth on the 7th March 2023 they told me that one of the injectors need to be Changed I was then told they need me to approve that they fill my car @ R200 today the 20th March they told me that they won’t fix my car underwarranty as my fuel Tank Have Dirty from fuel so I’ll have to Pay and my question why they never picked the problem in the beginning and what’s the proof that Dirty is coming from my Own Fuel