Sounds like Royal Mail offered them a pretty good pay offer and it is the workers that are holding out for more.
I might have some sympathy for the workers if Royal Mail offered them a derisory pay offer but 7%+ is a pretty decent increase. It is below inflation but not many people are getting above inflation pay rises.
They are using their customers as pawns which I suspect will not be forgotten when people choose who to use to post parcels and letters going forward.
You need some TP to wipe the brown off your nose with how far up RM's ass it is.
7% over 2 years is not a good pay rise, especially when it is tacked with conditions that result in crappier working conditions for employees. You are out of your mind.