Extremly Poor Service

I have purchased a Toyota Etios in 2012 from Toyota Mobeni and have problems with the vehicle since then. Every time the vehicle went in for a service I had complained and told them whats wrong and they did nothing about it. To date I was promised that they will assist with one of the issues being the accelerator cable keep getting stuck and the engine being very rowdy as the oil does not flow as it should. It makes one to wonder what happens when a vehicle goes in for a service do they really do what they should. The car now feels very unstable on the road as the steering wheel has a knocking sound and the accelerator keeps jamming. Should something happen endangering lives of others and myself who will be responsible for this.