Poor service at Malelane Ford Dealership

on the 9th of June I brought my car for service ford fiesta 2018 1.1, same day i experience engine problems, and some engine warning lights, i then informed them on the following day and it was taken to the dealer in malelane, without them calling me to ask about the symptoms of the problem what i god the on the 11th i found my car stripped the the whole dashboard by a mechanical technician.

and a week later i was presented with the invoice of 35000 to repair the car, and i said this car is under warranty and you did your own stripping without informing me and you never communicated with me since you are working on my car, they told me that they have escalated the matter to the manager, its been 2 week now the manager have not responded and my car is still stripped, please advise what should i do now