Nico from car care clinic midrand is very dishonest!

I took my car to Car Care Clinic Midrand, as per usual for service.They didn't change the plugs in my car and didn't disclose that to me, I paid for the plugs however.When I approached the manager Nico,he **** and told us that those are platinum plugs hence not replaced.I then bought myself plugs and fixed the car,Nico promised to give me a discount next time as I was charged for plugs and they didn't do the plugs, I took the car there today and he tells me that he's closing today and he won't give me my refund for plugs back or service the car today with an attitude. Nico is very dishonest, I am asking myself whether they have been replacing the other things in the car as this is not my first time servicing there.This clinic cannot be trusted, I am no longer taking my car there and I want my refund back!!