Hi Alan
The first dealer made a massive error in deleting the codes without keeping a record of what the codes were?
Normally someone diagnoses a car by recording the fault codes, deleting them and then taking the car for a test drive to see what codes return.
It’s not difficult so they should be able to get to the problem quickly.
Ask mobility if it’s possible for you to have a case manager to liaise with the dealer.
As for returning the car it’s a bit soon for that, but if the car keeps having the same problems then the case manager will be more likely to acknowledge your problems and get the car changed.
good luck and I hope they can sort it this time.