Insensitive . . or what?

Just after I was diagnosed in 2009 I was invited by some department in the NHS to take part in a bowel cancer screening programme. I ignored the first letter but after the second invite I contacted them and explained that I was already under investigation/treatment. This week, after two operations and while on my second chemo regime, I've received another letter . . . inviting me to take part in a bowel cancer screening problem. I've telephoned and explained the situation but they are insisting on contacting my GP for confirmation before removing me from their mail list. 

Now I'm quite thick skinned and was more annoyed than upset, but how distressing it must be for some patients to receive such correspondence, and even worse for relatives of people who didn't survive.

Surely something can be done to prevent this sort of insensitivity.