Bank Holidays When Saleried

Really need some advice,
our workforce is currently going through the collective grievance process, with regards to the WTD hours. We are Salaried to work 45 hours per week (5, 9 hour shifts). A new manager came in and changed the way our WTD hours are recorded, they now only record holidays as 8 hours per day and do not record bank holidays at all as part of our working time directive hours over a 17 week rolling period. Previously this has always been recorded as 9 hours on both the previous issues. I am aware they do not have to record hours for bank holidays towards your WTD hours. However this rule (in my opinion) seems to be for those drivers who are on an hourly paid contract not a salaried contract. We are currently 92 hours per year out of pocket which means that we have to work an additional 184 hours per year to bring our WTD hours back to 45 hours average per week. Surely this cannot be right.

Your help is appreciated.