Upvote:3
Having more than one Schengen visa is not allowed, and extending one is impossible. Cancelling it should not be hard but bureaucracy of the embassies/consulates are a pain in the ass sometimes.
The only way to get out of this is luck, for example if the passport was accidentally clipped, or accidentally some water was spilled on it, the passport will be damaged then you can apply for a new passport and then apply for a new Schengen visa from any other EU embassy. But again, only if you are lucky ;)