Bank holiday entitlement

I work 3 days per week (22.5hrs). My annual leave sheet says my annual leave entitlement is 153 hours - excluding bank holidays. If my working day falls on a bank holiday they deduct the hours from my annual leave sheet. If 153 excludes bank holidays then would that mean I need to add on bank holidays accrued pro rata? I don’t understand why this wouldn’t be noted anywhere? Im trying to figure out exactly what annual leave I’ll have to sort what to take after maternity leave.