My trick for getting anything done is to be exceptionally nice and polite and then say something like “it's so interesting that you can't/won't speak to x, and x can't/won't speak to you. I never knew it worked that way and would be so difficult for an ordinary person like me. I've got an appointment at my MP's surgery tomorrow and I'm going to mention this to him/herâ€. 99 times out of 100 that is enough to get someone to do what I want!
Tc - so I suggest an email to both GP and consultant explaining how absurd it is to expect a bereaved lady who is struggling with her own health issues to act as a intermediary between two health professionals and that you are seeing your MP on another matter and you're going to mention this to see if it's right because you think it can't possibly be!
P.s. You could argue that it doesn't matter if this gets their backs up because they couldn't be more difficult than they are already being!!!