Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

Is it a very difficult job ? I've seen some plastics at the bottom that hide the seat belt case and also it seems it's in a very restricted position...

Do you have to remove the seat to get to the seat belts ?

The seats need to be removed. Not a difficult job but as you say some bolts can be a bit awkward. Make sure you use plenty wd40 or similar on the bolts before you start as I've seen a few posts about rounded bolts/torx.