I want my Refund Back! They Claimed to Service

So i took my vehicle to Carlos W Motors for a Service and when I went to collect my car I was told that my vehicle has been serviced. But I received no Invoice nor Job Card. Soon I got home the car was as I have brought it to them. Now when I phone them their Lady in Reception Serena Horn is giving me attitude and claims they have indeed serviced the car I want my Money Back!