Hi Alice50
Thanks for your post. The default Superannuation Guarantee payroll category is preset with the ATO reporting category assigned as Superannuation Guarantee and can't be changed.
Salary sacrifice amounts are only entered against the Salary sacrifice payroll category to reduce the gross income. As such, salary sacrifice amounts shouldn't affect Superannuation Guarantee.
So that I can look into your issue can you send a screenshot of a salary sacrifice pay transaction. Please make sure sensitive information is removed from screenshots prior to posting on the public Forum.