Fiberglass repairs are actually relatively easy to effect, and if done as a DIY project, the materials costs are not exorbitant.

There are many instructions available on the Internet. Basically you open the cracks, exposing the layup layers. Then adding like materials and resin, you build up the cracks and usually add an additional strengthening coat above the cracks. It's very much like mudding a dry wall seam.

 I don't know what type construction of which the stall lining is constructed. If it is fiberglass, again it can be repaired and if necessary, further reinforced and strengthened with additional layers of FRP materials.