From what u can see in Vauxhall website if you wanted to get one in pcp or lease it’s an extra £700 for the blue as is not a standard free colour. So £280 for it is pretty good tend to find black, red, silver or white only tend to be free and also depends if solid or metallic colour. So is probably right and dealer may have not realised when ordered the colour was chargeable and I know not your fault but I’d pay it if you really like that colour or wait for one in different colour. You get £250 towards next vehicle of mb so could look at it’s only £30 for the colour