Originally Posted by Nick Art

I do however not know if you buy or bid for an upgrade into which letter class (important so you know how many miles you'll earn) you will be upgraded. Is it always the same? (Can't be I as the flight does and should earn miles) Or is it due to availability? (In which case most upgrades would be put into C or J as those are often the last ones left, but I don't really see that happening), If somebody could clear this up I'd be thankful.