In the back rest of my seat some kind of padding slipped. There is a thick ridge now on the back rest and it goes into my spine and hurts really bad. I don't really like seat covers, but I guess I will buy one if I have to. But before I do, is there a way I can get inside of the backrest of the seat without cutting a hole in the cloth? I would really like to fix this myself if I could.

 

http://www.volvoclub.org.uk/faq/Inte...eatBackRemoval
There is a whole section about seat repair. You might find something useful in there.