This may not be worth the hassle but I believe in putting my foot down when you get screwed like that - the windscreen replacement sounds terrible, I'd be back demanding they redo it free of charge and do it properly - if the rubbers are not making a sealed contact with the body you will get leaks, rust, smells etc over time!
If they refuse, threaten to bring the Trading Standards people into it?
I know more often it's not worth the grief but that sounds like a serious failure to me to do the job you paid them to do.
I had to have a rental car after a not-my-fault RTA a few years back while my Mondeo was in for repairs - Astra estate turned in front of me and I slammed into his side - when I went to pick it up from the 'flagship' Ford Main Dealer on the A13 at the Dagenham works, they put the wrong grille on it, left the radiator cowling in the boot along with some unknown fixing screws, oil on the rear floor mats with a half empty can, rubbish in the front footwell and a four inch scratch on a brand new wing...
I walked back into the office, took the hire car keys off the desk of the person I gave them to, told them to sort it and that I'd be keeping the hire car at their expense until they did it properly!
Needless to say, they protested but I wouldn't argue with them and when they came out and I showed the guy, even he looked surprised so obviously hadn't checked the car before calling me.
I got a call three days later and this time it was spotless and all faults rectified! :oP
I'm no ogre though, I'm a big softie really, just learned that a stern look can acheive many things!
