The fight to keep a town centre post office open has been backed by the council.
The Post Office wants to close the branch in Sutton's St Nicholas Centre and merge it with the branch in Grove Road.
But Sutton Council has joined campaigners who say the move would be problematic for customers, especially the elderly.
The council has also criticised plans to franchise the post office in Wallington - meaning it would have to find a business parter to operate alongside.
Councillors unanimously agreed a motion to write to the Parliamentary Under Secretary of State for Employment Relations and Consumer Affairs and the Post Office, calling for the St Nicholas Centre branch to be saved at a meeting on Monday night.
Liberal Democrat Councillor Colin Hall said: "This will have an effect on jobs and services for the most vulnerable.
"It is essential we stick up for the post offices we have left.
"This is a call to action, it's time for us to stand up for the residents of the borough."
Coun Peter Geiringer added: "The plans to close the post office in the St Nicholas Centre will mean a long trek uphill to get to the post office in Grove Road. The elderly will be affected."
Plans to close the St Nicholas Centre branch and franchise the Wallington branch are part of a scheme to cut losses. The Post Office says its 370 crown branches - those that are managed directly by the Post Office Ltd - are losing £37m a year.
A Post Office spokesman said: "As part of our plans to bring this part of our network back into profit we are proposing to merge the High Street Sutton Crown branch into Sutton Crown branch which has the capacity to accommodate extra customers and is within reach of High Street Sutton branch. Sutton Crown Post Office would be fully modernised to make it as easy as possible for customers to access services prior to any move taking place.
"No final decision has been made and before any move takes place there will be a 12 week public consultation process to allow customers and interested parties to give us their views. Any merger would take place before April 2015."
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