Plastic, and fiberglass are not the same, and probably not compatible. If your material is plastic, try a small application of epoxy in a not critical area to see if it will work.
DIY Guy
January 2017
you could try using fibre glass and resin to repair it. available at any decent car accessory shop.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix baths and showers.