I've waited a 1/4 of a year now for a reply
To be honest, that's very unusual, and is not borne out by my experience of communicating with Aviation House. There may, of course, be something of which I am not aware which makes your case unusual or difficult.
However, periodic enquiries over a reasonable time scale can always be made to see how things are progressing. General number is 01293 573 700 , you get through to one of these automated synthetic operator systems. You press "1" for Medical, then get four or five other choices. My advice would be to ask to speak to one of the Aeromedical Advisors.
At the very least they should be able to help explain why it is taking so long to make a decision !