Try a mobile fiberglass repair service. Usually building materials dealers will have contact numbers for people who repair bath/shower units after installation in homes for "in construction damage." During 15 years of managing/owning apartments I have used several such companies. It is an excellent option, opposed to doing a complete bath renovation, when a tub/shower combination unit is cracked or otherwise damaged. Such repairs are almost impossible to find unless one knew exactly where the damage/defect was.