Belt noise

If he replaced the tensionier and the belt, it sounds like something is getting on the belt to cause the noise. Check to make sure nothing is leaking on to it such as coolant, power steering fluid. Also, you may want to remove the belt and clean all pullies that could have dirt or grease on them. I always use something like brake cleaner (non-flamable type). I spray it on the pullies and wipe them down with a clean rag to make sure they are clean. The brake cleaner evaporates in a few seconds.