OVERTIME ON A BANK HOLIDAY

[postmanprat]

hi
whats the ruling on overtime on a bank holiday?
new start / finish times in glasgow mail centre ( new 22.15 06.15)
in the past royal mail would start us before 22.00 that way we got choice of double time or normal time and day in leiu
now after change if start finish time we are being told that no leave in leiu will be granted
under the way foward we are able on normal over time shift to hand it back giving 24 hrs notice
but when its a bank holiday we get the the phrase "adjustment to working week" or "bulk docket"
this is we are told not a single shift ie 8 hrs on monday / tuesday but over time spread over the week
1 is the bulk docket / adjustment to working week a true statement?
2 can this be handed back?
we have been told if we dont turn up we will be marked down as awol
ta