I have not tried them myself, but, yeeeears ago, I used to work for a car rental agency. We used to have a guy come out once a week and fix all of our chips/bullseyes, and cracks. He was even able to fix a 15 inch crack once. I never had to call him back to re-do a repair.
I would see what a Professional charges, and have him do it. The main reason is that they will usually give you some sort of warranty.
"...rationality of thought imposes a limit on a person's concept of his relation to the cosmos." -Nash
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09 Jetta TDI