How accountable is advice from a chain auto service garage? Their advice cost me my car. It now needs a new engine.

My oil light flickered on so I took it to a chain auto service garage for an oil change. I came out of there spending over $500 for brakes, pads, rotors and inspection (not due for another two months) and of course, my oil change. They performed a full complimentary check of my car. They said my car looked great with the work they did. About a week later, my oil light came back on and stayed on. I decided to take it back to the same garage because maybe it meant that something was wrong. One of the mechanics test drove it "hard" as he put it in order to see if anything would happen. Nothing happened. At that point, the mechanic dismissed the problem as a bad sensor and never took it into the garage for a full check. He said to ignore the light that the car was fine; I did just that and my car broke down later that day. It was towed to two additional private garages that confirm the engine died. I told them about the oil light and they couldn't believe I was driving around with it lit. I went back to the chain service garage and they feel that they did nothing wrong. They said they gave their educated opinion and if I didn't like that, I should have taken it to another garage. I am out of car now when two weeks ago, my car was fine. Do I have a case against this particular automotive chain? - Is this your question? Add additional information