VW KEMPTON PARK BAD SERVICE

I took my tiguan R line for a service 3weeks ago at Lindsay saker vw Kempton park on my arrival i informed the service advisor that the vehicle fuel consumption is heavy, i collected the vehicle and the service advisor by the name of Funi informed me that they performed various tests and the vehicle showed no problems. I then took the car but the issue still persisted my wife then contacted them and confirmed a booking and they booked the car but never i formed my wife that the vehicle would be staying there and they don't have a courtesy car however the service advisor Funi told me they would have a vehicle the following week which was last week and that she would make the necessary arrangements with me I'm still waiting till now im not satisfied with the service i received from the said dealership