Miles to next service: variable or fixed?

Like many others I thought the garage had reset my car to fixed interval servicing after its last service because straight after the service it said 10,000 miles to go to next service. I told the garage what I saw and they said they thought they had reset variable but I decided to leave it as fixed anyway as I think oil changes are no bad thing for an engine.

However I have just noticed this morning that my car now says 8,500 miles to go. But I've done 6,500 miles since last service so I guess the car was reset to variable servicing after all!