Diagnosis of cylinder head gasket

Hello, despite the minimum 82,000 km our Sabb Cabrio, Bj 2001 now has a problem – the cooling water disappears. Otherwise it is appropriate nothing to notice – only that the corresponding message always appears in the display. After 4 days driving across the city – me many traffic lights) since the diagnosis almost 2l new liquid got. But after a short time the display shines again. Therefore urgently and quickly what has to happen … Lack of brand workshop i In the area I have always had a few small gypsies done at ATU, which I found perfect. Now they have given me this diagnosis, but can not carry out the repair, because only parts have to come directly from Saab – and certain special tools are not available. Now I have read several times that it could also be the screws from the head … but I have to say that on the front area and right (if you are standing in front of the open bonnet) Olsuppe can also be seen, d he runs up under the block. Not so that you can see any spots when parking – but nevertheless probably no Lapalia. Therefore my question into the forum, whether someone has an info, what I could possibly check (with the scrubs – does that come into question at all?) and where in the area Potsdam or near Berlin a good and price-fair workshop can be found? Thanks for your information and help Frank