Salary Sacrifice Pension should reduce gross pay

I previously raised a case regarding salary sacrifice pension, when i tested salary sacrifice pension i noticed that it does not reduce gross pay but it should reduced gross pay, if salary is £3000 and salary sacrifice is £250, gross, NI'able and Taxable pay should all be £2750 but gross still shows as £3000, which is incorrect. I was also told that gross pay is used to calculate statutory figures, which is also incorrect, it should be NI'able pay. Can you please fix this.