Shower recess blistering and crazing

Sounds like it is glued into place and they have used an Acid cure glue when they should have used Neutral cure.

Did a cool store once with fibreglass panels and the contractor supplied the glue and the whole place bubbled. Found out that was the cause. The acid cure glue caused the bubbling in the panels and on replacement they were ok with neutral cure glue.

Doobee,
sounds to me like the bond between the gelcoat and laminate substrate is not their or the glass was laid up dry over the gelcoat. From my view point there is flexing between the glass and the gelcoat

The only fix for this if it is happening over large areas, is for the cubicle to be pulled out and replaced and that will be a pretty big job.

It may be worthwhile getting a second opinion from someone in the fibreglass industry, you can probably find someone local, when negotiating repairs you can never have too much information if they are only coating over the top and covering up a bigger problem what happens when the warranty runs out ??
Like said above if its a glue problem the only real fix is replace the shower
Kev

When a fiberglass boat or in your case shower recess is laid up ( in the mould) the gel coat is sprayed on the mould first. Then the first layer of mat and resin is applied and the air bubbles rolled out. This process is repeated until the required thickness is reached.
Your problem is that the air bubbles were not rolled out properly when the first layer of mat and resin was applied.
If there is only a few air bubble holes they can be fixed like the first ones were done.
The problem is there will keep appearing until they are all exposed.
Get am independent fiberglasser to give you a second opinion. Cheers Brian.