Tire Choice review: Oil change turned into a "nightmare" 1

Took my car into "tire choice", for a routine "oil change". The manager, came out after about a fifteen minute wait, and stated, my gasket, needed to be replaced because of a "leak". I told him I would bring it in tomorrow, (meaning thursday, may 6th). He would not let me have the car back! I felt somewhat intimidated, however I did not know whether the car was safe too drive. After waiting "all day", (arrived 10:15, 45 minutes earlier than my appointment), from 10:15 to 6:00pm, I was told the mechanic, put back the parts, which he first removed, and heard a "grinding noise". The manager said, the mechanic, was "off", on thursday may6, and would not be in until friday, may 7th. Long story "short". I don't know whether the car will be repaired properly, or not. I am without an automobile, I am a "senior citizen", with a disability. The bill of over $600.00, was given to me, before I left for the day! This is a "total nightmare for me! They want their money don't they? What do I have? No car, no"respect"!