It's normal practice to use marking tape to support the screen until the bonding sets, to prevent the screen sliding down slightly in the aperture due to its weight.
It's not however to use masking tape to hold down the surround at the top of the surround until whatever adhesive they have applied has gone off. On the later cars, the surround basically clips into the retainer round the screen, and needs no adhesive or goo, but I don't know whether the surround on early models are secured the same way.
The rubber looks totally deformed in your pictures, and the bottom seal is far too short, and in my opinion these should clearly indicate to them that the fitment isn't as it should be.
When I had a replacement screen fitted years ago, the fitter then said that it is important that the screen is fitted to the correct height (to clarify- the correct amount of bonding is applied so that it sits at the correct height in the aperture) otherwise the seals that are a push fit into the retainer don't sit correctly, usually sitting proud due to excess bonding, hence the need for goo and the marking tape around the seal in an attempt to get it to fit to the surrounding bodywork. He also said its normal practice to fit new rubbers with a new screen.
I have also heard that some none Vauxhall screens have an inferior retainer around the screen which can also contribute to fitment problems, ie rubbers that sit proud or pull up at the top corners exposing a gap between the rubber and body.
I would demand that they return and refit it with new rubbers by someone who actually knows what they are doing! That is assuming new rubbers are available for your age of car, and the aftermarket screen is of good quality and correct profile which in itself could cause fitment problems if it wasn't ......