We took my husbands truck in June to have oil changed last week the oil light come on and it started knocking bad. I took it back to them and they said its fine sounds like a belt. Mechanic said they didn't put but maybe two quarts of oil in a 6 quart vehicle. They charge you for like 5 quart oil change and put half what you need in it. Now I have to $300 to fix their mistake. I need help