Salary Sacrifice for those on maternity leave

The salary sacrifice pension does not appear to be working correctly for anyone on maternity pay. The employees pension should only be working on pensionable pay e.g. OMP, not SMP but the employee is currently having too much employee pension deducted. The employer pension is not being topped up by the shortfall either even with the APP is added to the maternity pay. This needs to be urgently amended so that maternity pensions are calculated correctly. SMP needs to be unticked where there is a salary sacrifice in place including pension.