Hello

Does anyone know if the following is true:

1) You can only upgrade by one class with BA air miles (so Economy to Business would not be possible even if I had enough air miles to do so)?

2) You need to book a flexible ticket in order to be able to upgrade?

We have been told this by someone at BA (on the phone) but I'm not sure if I can trust this information as points on the BA website that suggest that this is not the case (though the info on the website is very ambivalent, hence my confusion).

Thanks a lot for your advise!

Anna