On the other hand, the NHS isn't particularly targeting anyone. If you aren't registered as exempt, the department dealing with it won't know. It's a bit like people using disabled badges for parking when not entitled. As diabetics, we might not like them checking up, but as tax payers we should be pleased that they are on the look out for people defrauding the NHS. Hopefully, once you explain, they'll drop the fine, you'll get your exemption card & everything will be fine.