VW,and scrappies.Vw owners sites will know of any vauxhall specific stores etc... try espdesign they have replica escort GTi spoilers and may be able to get u the polo rep.
Tail-gate spoiler for Polo (1999+) This spoiler is manufactured from polyurethane plastic (sometimes called PU rim). This is the same material as used by large car manufacturers for their original equipment spoilers. Fitted using the bolts which are included. The tail-gate will require drilling – this can be carried out quite easily using the templates provided. Full instructions are included.
Info from
ESP Design Website