Greetings,
On my last trip returning from Ulaanbaatar to Europe the staff at MIAT charged me 24 USD/kilo for excess baggage as opposed to their stated rate (on their website) of 6 euro/kilo. MIAT staff had already loaded my bags onto the plane then sent me over to the ticket office. By the time I realized they were intending to grossly overcharge for excess baggage, my bags were on the plane. It took nearly one hour for the extra bag to be pulled off the plane as I wasn't willing (or able) to pay 1,000 USD to have it flown back to Europe, and I nearly missed the flight. (By contrast, Aeroflot charges 50 euros for a second bag of up to 23 kilos.)
Anyway, just a heads up to anyone flying out of UB with MIAT -- their excess baggage charge practises seem to be very dubious. This also happened to other passengers I spoke to on the flight.