Automia laziness and disrespect

Amount of R40,940 was deposited into Automia account (7th May 2019) for a fitting of a used engine supp**** by themselves. On the 27th June 2019, my car was delivered to their workshop with which I was promised that the car would be fitted with another engine and ready in two weeks. It is the 27th of August 2019 now and my car has not yet been attended to. I decided to cancel the requested service, Zahir (mechanic), refuses to make a refund. He says I can come and pick up my car (without being repaired) but they will not be able to refund me...