I recently purchased a Paph Greta Kooiker online and it arrived with yellowing and damaged leaves. Is this a symptom of disease or is it due to stress?
I agree with Ray's diagnose.
You could water it with an Epson Salt solution to increase magnesium but the best is to give it a balanced fertilizer.
Maybe some of the US members give you a brand sugestion as I'm not familiarized with what's in your market.