1995 Vauxhall Tigra rubber seals on the back are old and coming lose and water come in to the boot

Hello readers are we sitting comfy..?
Then I shall begin. I have just swapped a 02 punto for a 95 Tigra (yes i know now)
ok I love the car from sight ..but like all love it goes cold.. The back of the car MK1 Tigra the black rubber seals are bubbling up and they have come off the top of the back window. Now you can still open the Back window but water comes out from the top and runs down the two side skirts.. at the base of theskirts there are maybe 5 small pin holes i cleaned these but the big problem is the rubber has now come away. I' have been to a Opel garage in sunny Germany where Im based and..sit down please.....its going cost 6 hundred euro's as i was told by the chap...the whole back glass hat to be changed...Is this really true..I tried to replace the rubber back on the rails ( in side the lip of the glass) but it seems to be streche'd at some point so it fits at one end and not in the middle. I have looked on line for this and don't know what to do.Blonde chicks and Tigra's that what I wanted....Many many thanks in advance.. Jamie in boys its really raining here in Bergen Germany