Door of washing machine sticking closed and won't release?

I have a Bosch Classixx 1200 express washine machine, which is developing a fault with the door. After the cycle, the door is meant to stay locked for a minute or so, but it stays locked permamnently. I have to wrestle the thing very hard to get it to open sometimes and I feel that in the next week or so it will stick permanently. Is there a manual override on these doors? It is an easy fix? Anyone had experience of this problem?