My car had a service engine light.
Was advised by Service advisor that I would need to pay diagnostic fee and if I chose to proceed with work, the fee would be credited against the service.
I ended up having sensor replaced, but they did not credit the fee.
Was only after some time that I reminded them, did they credit me back. But they said it would remain at the dealer for a future service.
After trying to use this credit, it turned out there was still no credit.
Finally Amanda was able to credit my original credit card back, but it took very long and was a negative experience having to find old emails to prove that I had paid.
However, the did repair my engine light issue successfully.