What would you do if you were told you have coverage but then they change their mind?

Before I had taken this job I needed financial aid assistance for my medical check ups trying to find out what was wrong with me. So I have assistance from the government. My doctor ordered me to wear a holter monitor for my heart which was a pain in the butt and useless.

Anyways, I was told by the financial aid company they would cover it and just to send the heart company (ecardio) the reward letter and it’ll be taken care of.

Fast forward 2 months later I get a bill yesterday that says I owe a whopping $500 for wearing a stupid heart monitor! I was so angry.

I called them and now the financial aid company says “Well your doctor just requested a part which isn’t associated with us so we can’t cover it” even though a couple months ago I was even given instructions!

I have no written statement so I guess I have no proof. =\ I’m not sure what to do here. I’m just so mad they said they would cover it and then don’t!