There could be a leak (you can do a bucket test, or a dye test first. A pressure test would come after both of these to pinpoint the leak, if you do have one.) That would be a way of lowering CH, unfortunately.
Filling a pool in can be really expensive (and I hope you are kidding. Pools are great and create many family memories; much more than a garden does, for example! Both are a bit of work, but pools do get a lot easier, especially if you stick around here!). Here we have to get a permit (we have to get a permit to sneeze, actually, but that's another story

), then demo out the floor and check for soil stability. Sometimes we have to remove some soil below the pool to find a solid foundation, and then we have to fold the top 18" into the pool itself. Gravel must be used to fill the majority of the remainder, and then soil can be placed on top. If you decide to move, you also have to disclose that there is a pool buried in the yard, in case someone decides they want to build a pool one day and discovers that little secret. Complete removal is somewhat similar, except you can use all soil, but it needs to be compacted and certified if you go that route.
In the end, a repair should be the least expensive, and you will have a pool that will last you many, many years. it is too bad that someone "cheated" along the way and that you are now paying for that poor workmanship. I don't like to hear stories like this, but I see it way too often and it is too familiar. Once again, the good news is that you have PebbleTec and it can be repaired, easily and almost invisibly. There is a lot of value to that.