I guess all they will do is put 12v on it. If they wont repair it or it costs say £50 he wont pay it as assuming i refund him the £100 a new one is £170.

But as ive lost out on the postage and ebay fees i made approx £75 from it so i wont be refunding the full £100 either.
I think ill give stack a ring myself tomorrow and see exactly what they do and go from there.

I have repaired a stack gauge myself before so it might be doable.