I had mine replaced by Autoglass and they used a genuice Audi screen. No complaints, I did have to wait a few days for them to order on in though. Personally I would go to one of their depots instead of getting someone out to your place of work.
Only because unless it is a perfect day, few and far between in the uk, any moisture in the air can effect the sealent.
They also replaced the screen in Claires merc.
Oh and if you have auto wipers make sure you remind them when you drop it off. It had to go back for Claire's as they didn't fit a new sensor, not sure if it is required in a audi though.
J.