I'd be calling the manager of the place that did the work for you the first time and having a nice long discussion with him about the quality of work that his shop produces. If that didn't result in an offer to have your Montero towed back in and repaired at their cost then I'd be mentioning the attorney general's office, the Better Business Bureau, small claims court, and the name of the lawyer you'll be calling. I personally think you're getting the shaft - make the shop repair their mistake.

You could potentially be looking at needing a new crankshaft in addition to the damaged pulley - do you really want to foot that bill yourself when they should be responsible for it?