Strangely enough, we've just had this very same problem. My husband was awaiting a diagnosis for Parkinson's Disease last week. The Consultant says he has a number of the symptoms but needed an MRI, so we had not received any letter of diagnosis. When I rang a number of travel insurance companies, all but one said they would not insure us whilst he is under diagnosis, full stop! If we had already got insurance, it would now be invalid anyway, they said, so that would have made no difference, and we couldn't have 'upgraded ' it whilst under diagnosis. We panicked as our long-saved for holiday to USA was within two weeks. (This was a holiday already postponed twice due to covid, and where we originally had insurance in place) Only Direct Line said that if we paid the premium for PD then we would be covered. I was wary as no one else was prepared to insure us, and what if it wasn't PD? How would that effect the insurance cover? I rang his consultant and his secretary said she'd do what she could to get the letter through as soon as possible, by hurrying the results of the MRI, but wasn't promising anything. Thank goodness she came through and we got the letter and the medication within days. Incidentally, I had asked the travel agent if we could postpone the holiday and he said no, as it was fully paid and it was too late, and if we had to cancel, we'd lose everything we'd paid as we had no insurance!! Catch 22 situation!! Yes, I tried Staysure - useless. And Saga were even worse - no advice whatsoever. I even rang parkinsons.org but they had no advice either except to say it is a common problem! No one was able to suggest a way round it, so thank goodness we got the diagnosis, and yes, of course, we went with Direct Line, as they were the only ones who would even attempt to suggest ideas, and offered to ring back in a few days to see if we could get further info from the hospital. I do hope you get yours sorted out - good luck! We need a holiday now to deal with the stress all this caused!