I wouldn't let one experience and one particular dealership ruin an entire plan. Each dealership deals with things differently, and that goes for Toyota, Ford, Nissan, Land Rover, Jeep, etc. Same can be said with their mechanics. Some are great, some are horrible. The only thing I will ever get from a dealership, if I NEED it, is to order parts or to check out new vehicles. I would never have them work on any vehicle of mine. I'm really sorry to hear how that dealership screwed you over on a job like that. Use that as a future reference to not use that dealership again, but don't let that be the lone factor to persuade you out of a great truck. Find a different dealership.
And how does a warranty service job become your fault? You took the Murano in for service; they wrote up the work order, supplied all the parts, they did all the wrenching. I don't get how they came to that conclusion that the job they did is your fault. Take it up with corporate. It's going to be a headache but these people need to know it was their own fault and that they need to pay for it. Not you. It's a warranty for a reason.