I might try and go again if I get the chance to see it the other way around, although it will probably be a little while before I get to London again, so it may or may not happen.
I did notice that there were some press folks there on Saturday night. I thought they might be getting the show in this way around before seeing it switched at the Press Night, but from the schedule it seems press night is also Kristin as Anna and Lia as Kate.
I can't help thinking it is very unfair to you if the schedule you booked under was changed. You have in fact booked for two shows which is what they want. Can't you ask them for a reduced rate for a third?