vanda turning yellow, drying

[Thriodien]

It's me again, sorry. One of my friend has trouble with both of her vandas. The first one has brown rotting on the flower spike. Actually the whole flower spike is rotting while the flowers are ok I guess it's fungus or something like that but i ask your opinion to be sure. The second is just simply getting drier and yellower every day. The "old" leaves fall off, though it is a completely young plant. So we think it's not a normal function and that i sould ask if someone came across a case like that. What can it be? The plants are treated well, like they should be, high humidity, fresh but not cold air and bright shaded/sunny window... We don't know that went wrong with them .