I got different quotes 550 main dealer (job done properly) .
Any decent mechanic will do the tensioners. You can buy the kit yourself and give it to the mechanic thus avoiding the rip off mark up dealers put on. I have not heard of someone doing TB and pump on a passat without doing tensioners. Its just part of the job.
As for the dealer stamp. I have never seen anyone called a liar or anyone put off by no dealer stamp. I dont see how a new timing belt should break immediately - then again you could drive out on the road and be hit by a bus..
Finally I cant believe those kerry timing belts/mechanics are so dear that it was cheaper to go to a dealer. Unheard of... They either seen you coming or the races were on that day.
Every other county in Ireland this is a no brainer on price and quality for reasons already given