blood donation

We one time got some information an our village about blood donation, that we should donate blood to save lives.
It was a group of health workers who came to our school, and encouraged us to donate blood, that one time a family member may need blood but if he or she presents a card showing that you donated, then blood would be given free of charge, but I donated and I presented the card, they refused to give it say that we should pay, but the confused me.

Location: Kaleerwe, Kampala, Uganda