We put in our Connecticut pool in 17 years ago. After a few years many tiles fell off in one area and after many calls to the installer with empty promises from them to come look at it and schedule a repair they never showed up and I finally found some one else (Good Guy Number 1) who repaired it and did a good job. His phone was no longer in service when even more tiles fell off in a different area in 2018. After many calls to the original installer, they sent someone out who seemed nice enough but couldn’t answer any questions because we did not speak the same language. I paid much more than Good Guy 1 for a smaller area. Then in 2019 when more tiles fell off, some in the same spot that were supposedly repaired in 2018, I emailed and called the original installer (who supposedly did the 2018 repair)for months and months and the daughter or daughter-in- law (same last name as the company )who staffed the phone always very nicely promised to send someone out but never did. Very frustrating. After more than a year of this I found someone else (Good Guy #2) who did a beautiful job for for about a third the price in late 2019. He is now retired. Now -2021-not only have tiles fallen off in yet another area but we found out that a big chunk of gunite behind the tiles was apparently never there. See photos. I called a bunch of places but they either don’t do good night pools probably say call your installer Any suggestions on what I should do to repair it? What should I fill it with? I’d like to learn to do it myself and have done a lot of major home maintenance myself because I have such trouble locating decent help for these repairs. Thanks very much.