giving blood - the problem

as some of you know, i try to give blood somewhat regularly - say three times a year. after last month's debacle (got letter from blood bank to ask me to get tested as i seemed to be anaemic), i thought things were back to fine as the tests were normal. not so.

yesterday i got another letter from the blood bank. seemed a bit much, as i couldn't see what else they'd want with me since i'd sent them said results. they thanked me. and asked me not to give blood more than once a year, as it could really result in me becoming anaemic. typical.

i started giving blood to feel like i was doing my bit, especially as i know they're always in need of blood. as it turned out, i can only give to research, having lived in the UK more than 6 months in a row (might have CGD) and now this. why are they so trying to thwart me?