other possible way of handling it is to try and agree to the third party to get a quote then you pay the garage/ smart repair company to do the repair that way its fixed.... and she cant spend the money on anythign else and not get it fixed
I'd play it like at least this way "if i pay the garage you know i'm not going to tell you to get lost and not pay you when you have got it fixed"
it also gives you the chance to discuss the repair with the garage so you do not end up paying over the odds for the oh whilst its in and seen as she is paying can you do this that and the other
how many MOT places do you know of that do body repairs?