Service interval reset - Octavia 1.9tdi 2008

I recently had my car serviced at a local garage as opposed to a dealership due to poor customer service AND service in general (but thats another story). I reset the service interval as outlined in the manual but noted it only resets it for the fixed engine where as mine is the variable service period.

Q. How do I reset the service interval to reflect a variable service interval?

Thanks