That "8 year or 130,000 miles" alleged timing belt service interval got me worried enough to check the manual in my 2015 TDI with 60K miles... The only mention I found for a service interval was 130K miles and no time limit is specified. The water pump is definitely part of the "long block"- Here's a link to VW's online parts book listing and illustration of a 2015 TDI long block, and it's definitely complete with even the covers and everything underneath:
https://parts.vw.com/p/Volkswagen_2...GI-Engine-Long-Block/51237555/04L100033D.html . The water pump and and tensioner failures are probably caused by VW's programming these engines to run too hot to pass emissions, it's routine for these engines to run oil temperatures around 100 degrees centigrade! So do your research, build your case, and keep after VW!
BTW, I'm in southwest Minnesota- What dealer treated you so badly so I can avoid them?