Thai are actually being a bit sly about this. I have been booked in F for over a week now, email confo etc from BMI where I used my points. I was able last week to go into THAI site and pre order my First meal etc. When I rang thai today they told me I have never been booked in F but have always been booked in Business which is clearly not the case as I have an email confirmation confirming this, also when I go on checkmytrip.com it actually says that the airline has cancelled one part of my booking and replaced it with another. If they are going to cancel service and downgrade F then thats fine I dont mind sitting in Business as there are far worst places to be but they should offer something as It is a downgrade of service regardless of how I paid for the ticket. British airways always have done in my experience.