My stupid f*cking 406!!!!!!!!!!

[C.A.R.]

Delete the map, return the car as 'not fit for purpose'.

You are quite within your rights to do that (well, not whilst the remap is still visible on there...)

Sale of Goods Act (or SOGA) means that you can get a full refund if you can prove the car is not fit for purpose - which 'limp mode' would suggest it isn't. You might have to give them an opportunity to put it right, but you only need to give them one chance to do this iirc.

I think this is probably the best way out, then find a few hundred more quid and buy another one in a more epic colour....