The last time I decided to an oil change between intervals in my
C 240, the FSS read "8,000 km A Service". After changing the oil, the FSS automatically extended the mileage by 1,600km reading "9,600 A Service.

I decided to do the same this time by chaging the oil betwen intervals. This time, the FSS read "3,200 km B Service". After the oil change, the FSS still read "3,200 km B Service". This time, the FSS did not extend the mileage after oil change like it did the last time. I thought it was supposed to extend to a new mileage, but it did not this time around.

Any ideas?

Thanks,
Johf