Bad service

I took my car to renault fourways because its gears are malfunctioning and I received bad service and to date I have not been attended to fully but I paid for the diagnosis fee and they are simply failing to give me the quotation i paid for.They dont care about customers and are simply in the business for making money. I dont see myself buying a renault in my life again and I didn't even understand why I had to pay this time because I get stuck on the road with their car most of the time.I regret buying a renault triber.