POST Office staff in Holywell will strike for the 13th time on Monday.
The workers will join staff at 371 other Crown post offices in the country in the latest walk-out.
Staff working in admin and supply chain functions (such as Post Office cash vans) will also take a first day of strike action in a dispute over pay.
The long-running Crown office dispute affects up to 4,000 staff and is over a pay freeze, plans to close and/or franchise 75 offices – including Holywell –- and cut up to 1,500 jobs.
Plans to axe and franchise Holywell’s Crown Post Office has been slammed by angry community leaders, businesses and residents.
They have in the past described the facility as the “heart of the community” and fear its relocation from the High street could have a knock-on effect on trade.
Dave Ward, CWU deputy general secretary, said: “We’re coordinating strike action across postal companies on Monday to increase the impact of the action and try and focus the minds of company negotiators.
“Post Office management is out of touch with its staff and customers over plans to close Crown offices and cut staff.
“The company is unfairly imposing pay freezes on both Crown staff and now admin and supply chain workers while senior managers have enjoyed significant bonus payments.
“These double-standards cannot continue and we hope to make progress in talks this week.”
A Post Office spokesman said: “We’re disappointed the CWU has chosen to take industrial action at a time when we are working hard to turn our business around.
“The union is calling for an above inflation pay agreement when last year our overall performance was a loss of £116m.
“We must reverse this loss of public money.
“CWU has refused their members a fair and affordable pay offer of cash payments totalling up to £3,400 by April 2015.
“We would also like to clarify that the Post office is investing in our Crown branches and our plans to franchise 70 locations will not result in closures or any compulsory redundancies.
“Strike action can only cost our people money, cause disruption to customers and threaten our plans to turn the business around and keep our branches on high streets and in city centres across the UK.”