Cracks in brand new vermeculite bottom

[cherob]

I recently had my 20 year old liner removed because of a leak.  When it was removed, the vermeculite on the sides needed to be replaced.  WE live on the water but never had any problem with ground water.  Had two liners one 7 years old and then the second lasted for 20 years.  They put a well point in anyway and took out all the vermeculite.  New was put in and it looked pristine.  They left this open for months because the pool installer was not the best with time scheduling.   They came and put the new liner in which did not fit properly after the pool was filled and was defective.  They then took out the liner and lo and behold the bottom of the pool had cracked all the way around like the piece had dropped.  I brought it to his attention and he said it was no big deal probably from the ground water, but never had this before over the past 27 years.  My husband said it looked like the prep under the vermeculite bottom was not even or high enough and caused the piece to completely break off all the way around.  The installer said no worried, we'll patch it and then put the liner in.  My question is, is this normal and he wants to patch today and put the liner in right away.  I feel like this is not right and there should be no cracks in this completely new vermeculite bottom.  Please advise.  Thanks.  BTW, he made me wait over 6 months for this project to get done and the pool was left without a liner for that period of time.