As I've already said the light function is checked according to the info given by ford, I don't know when they normally go out, but if normally after 3 secs or so you could try what you have suggested.
Personally I'd be either getting your money back, or forcing them to fix the problem.
It's a bloody piss take taking the money for NOT fixing the fault, bit like paying for a meal and not getting it, but still having to pay for it.
tabetha