Can the serpentine belt be tightened on 2015 4.6L

My serpentine belt began squealing upon start-up about a yr ago. Sprayed some dressing on it and fixed the issue for a few weeks. Then had the belt replaced....but more squealing.
Took it to a different shop and had belt replaced again because it was not aligned properly and I thought it may have been damaged...also had tensioner replaced....STILL squealing....
Mechanic said it may be the build up of dressing causing it....applied degreaser & power-washed.....NOPE...still squeals.
Been to 2 shops....5 total visits....pulling my hair out!
Any suggestions? Can the belt be tightened? Are the mechanics just idiots?
Ive spent $700
Thanks

 

Your squealing could be a bearing instead of a slipping belt especially since you've tried many fixes.

Lots of rotating things on the front of our engines in addition to the belt tensioner: idler, water pump, fan pulley, PS, AC, alternator.