'milage' accuracy

The previous owner of my wrx bought the car from an import specialist, the milage on the clock said 55000. This would have been KM? The garage converted the speedo to MPH and 3 years later the milage currently reads 81000. Surely the actual figure works out as:

55000km = 34175 miles. 34175 + 26100 = only 60275 miles on the clock?

The only reason i ask is because I was wondering about the servicing intervals, Major one at 90000? and obviously if I ever sell it on, which is never gonna happen!