Is it common to have an oil leak after changing a timing belt? I brought my 03 xterra 6 cylinder manual transmission  to what I thought was a reputable shop in Albuquerque (Japanese care care) for a timing belt change at 164k miles. They made several careless mistakes including forgot to reset the timing and the car was running horribly when they gave it back to me. They finally brought in their lead mechanic who got it running perfectly and I was so relieved and happy but the next day I noticed a puddle of antifreeze  under my car due to a hose clamp not tightened which was easy to fix but then I noticed an oil leak coming probably from the crankshaft seal which is one of the seals they supposedly replaced. Now I am wondering if I can trust them to repair this leak or should I take it to Nissan who will charge allot of money but at least I can trust them. Is this a common occurrence? How can we protect ourselves from mechanics who seem to have a good reputation but make these kind of mistakes? Are they legally liable?