pfft rubbish everything can be repaired
this is how i would do it bear in mind i am only amatuer/home hobby body repair and its only things i have picked up building kit cars and doing small mods myself (although am respraying my whole car soon!)
With fibreglass there are a few tricks.
Before anything Get some panal wipe and scotchbrite pads, EVRYTHING must be clean and keep cleanign everything inbetween each step everything you try bonding to either paint filler or fibreglass must be given a key with the scotchbrite.
first one at the end of the crack drill a 3-4mm hole. this will prevent the crack spreading in the future once the repair is complete it basically stops the crack having a path to follow.as said also cut the crack with a grinder slightly mainly to "clean" it and provide a good surface for the filler to stick to.
next once thats done get a fibreglass kit and build a few layers up behind it make sure you wear gloves as its the most annoying sticky and horible stuff to work with (pubes covered in tar comes to mind). build up a few layers of matting 4-6 should be sufficeiently strong.
then get your upol filler out and start smoothing the crack + hole you made filler shold NEVER be thicker than 5-6mm MAX ideally less so dont go slapping on tonnes of it. The less filler you can use to get it smooth and shaped the less work you make for yourself.
sand with 36 to shape using a sanding block (never just use your hand the larger the sanding block you can use for the job the better the job will be too), then start going down the grades to 300ish, check with a Guide coat to make sure there are no low spots in the filler. ( a guide coat is just spraying on a small amount of matt black as you sand the paint is removed, the areas the paint is not removed is obviously low keep sanding until all paint is removed, reguide coat then move to finer paper.)Sanding shold be done in an X type motion a few diagnal strokes one way then a few the other, this utalizes the square edge of the sanding block circular sanding is not ideal.
once you think your happy with the finish get some panal whipe and wet the repair, then run a light over the repair so you "follow the shine" with your eye you will be able to see any imperfections and it will give you an idea as to how it will look once painted, if your not happy resand dont have the opinion of "that will do" as it will look rubbish once painted if you have pin holes add a filler stopper putty or poly filler to remove them you only need a very small skim of this as it does not go very well in thick layers and can cause big problems.
once happy prep the surrounding area with scotchbrite just to key the paint for primer
mask up when masking backtape that means you fold the tape in half over its lengh so your not sticking the maskign paper directly to the panal but to the backside of the tape, this method will leave you with less lines/steps to buff in when the job is done and will give you a smoother paint blend.
then its just a case of primer + paint, if you have done the above correctly then primer + paint will be easy as long as you follow the correct flashing times and apply it correctly.
Good luck
i am so mad guys i cant get my front bumper fixed its cracked at the left hand side and i got somone down to look at it and he said its unrepairable does anyone know or can sort this out for me its a FiberGlass Bumper as well?????????? Please.