Upvote:4
No, Schengen days do NOT carry over. Under very few circumstance can you stay more than 90 days in any 180 day period with a short-stay visa.
Schengen Visa Code says:
In certain cases, the period of validity of a visa may be extended
They do not go into further detail than this, but adding days "because you didn't use them" will most definitely not work.