Bank Holiday for leavers

We include bank holidays within our AL entitlement (as have lots of part time staff who are only entitled to a pro rata). When we use the leaver wizard it doesn't take into account the number of bank holidays that have fallen so far - it just appears to divide by 12 and calculate by the number of weeks worked before the leaving date. This gives the wrong figure (as there isn't one bank holiday per month).

The system needs to calculate the number of bank holidays that have fallen prior to the leaving date.

It has meant we have to do manual calculations and the system isn't providing what we need.