You can cheaply repair fibreglass tent poles back to original strength with a fibreglass repair kit from your local auto parts store. The repair kit will include fibreglass mat, resin, hardener and directions on how to mix the resin. You can also buy replacement tent poles for less than £6, which can easily be switched out with a damaged pole. Replacing the poles will probably be the cheaper and easier solution of the two.
Sand the rough edges of the damage smooth using 60-grit sandpaper. Scuff 6 inches of the pole on each side of the damage so there's no shine left on the pole.
Using a hot glue gun, glue the pole back together in a straight line if the damage is all the way through. Let the glue dry, and cut any excess off with a razor knife.
Cut three layers of fibreglass that will wrap around the pole. Make the first layer 4 inches wide and each following layer 1/2 inch smaller than the last.
Mix the resin and catalyst in a small bucket following the directions on the containers. Use a paint stir stick to thoroughly mix the resin.
Wet the surface of the repair area with the resin mixture using a paintbrush. Apply the smallest layer of mat to the pole with the damage directly in the centre of the mat. Saturate the mat with resin using the paintbrush. Apply the next two layers of mat following the same process. When all layers are applied, remove any air bubbles that will be under the mat using an air roller. Let the fibreglass harden.
Sand the fibreglass smooth using the 60-grit sandpaper.
To replace a tent pole, simply remove the damaged tent pole from the vinyl loops that are holding it in place, and then pull the tent pole in one direction until it's completely free. Place the new pole through the loops starting at the bottom loop. Feed the pole through each loop until it's secured by all the loops.