How do you get a visa extension while living in France?

If you are currently staying in France and want to be granted a visa extension, you will have to apply for it in the "préfecture" of the department you are staying, or a "sous-préfecture". If you do not know where it is, just ask at the town hall or follow the link.

You will be asked your motives for an extension, plus all the same questions you had to reply to for the visa proper.