The Metropolitan Transportation Authority should delay its vote on fare and toll increases until spring, a group of 10 civic organizations wrote MTA Executive Director Elliot Sander in a letter made public yesterday.The organizations, including the Regional Plan Association, the Straphangers Campaign and Transportation Alternatives, argue a vote should not take place until March 31. That would be after the State Legislature has considered a traffic congestion mitigation panel's re- commendations, which could include new funding, and after the MTA has submitted its capital rebuilding plan.MTA spokesman Jeremy Soffin, in an e-mail statement yesterday, said, "Our financial plan puts the MTA back on sound financial footing while actually increasing service to our rapidly growing ridership. Delaying its implementation will only lead to larger fare increases and unacceptable service cuts."