depends on the Damage. if it's pretty serious cracks, where there are visible parts gouged out of it, Bondo (Isopon 38 is the closest equivalent in Europe, don't know where you live). cover the damage over, fill the cracks, then sand it smooth. of course if bits have actually been broken Off, you'll need support underneath the Bondo.
i mean, being that Bio's are from the looks of it Standardly Resin, which i'm guessing this one is, that should do it no problem.
Thanks for the prompt replies.
The BIO has only got a smallish chip in it and its resin.
The C3PO is worse, not cracked. Its in fibre glass and needs alot of tidying and filling/shaping....not a job i've done before.
For small chips, bondo putty or equivalent is great (I'd think you'd find something at halfords or similar). For larger repairs/reshaping as you mention with the C3PO head, I'd go for the body filler, again somewhere like halfords or a small auto repair place should stock something that will work. I've heard the Isopon 38 is more or less a direct bondo equivalent and that would work great. Be prepared to do a lot of sanding though.