..... Oops,hit wrong button !.
I'm surprised that your garage cannot deal with this,they should be able to sort this problem with easily.
Another way to get them out is to find a suitable "Torx" type socket that is slightly smaller than the head of the cap screw.Fit it to a short extension bar and hammer it on to the head of the cap screw,nice and straight with a club hammer,apply heat with a blow lamp (pouring the hot contents of a boiled kettle or using a hot air gun will assist anyone trying this at home

).
A competent garage would have oxy set up to do this.They could even burn the heads off as a last resort.
Sounds like your garage has lost the plot
