The union previously withdrew strikes planned for November 12 and 14
Royal Mail workers will stage two 48-hour strikes around Black Friday and Cyber Monday in an escalating row over pay, jobs and conditions.
It announced strikes around Black Friday on November 25 and Cyber Monday on November 28.
The union has withdrawn strikes planned for November 12 and 14, saying it wants to take more “proportionate” action.
An offer made by Royal Mail on pay and conditions on Monday was described as a “surrender document” because the union said it involved attacks on terms and conditions as well as redundancies.