Approved and authorised my drip and now refusing to pay from my hospital benefits as was approved

I had an infusion approved and got an authorisation number from Discovery. I received email proof of this that I must get the drip as an out patient, but everything will be paid for from my HOSPITAL benefits. Only to find that the Wilgeheuwel hospital pharmacy can't follow instructions and billed it from our savings. Thus depleting our savings and charging us out of pocket as well. I sent my claim in for the drip medication that we were forced to pay out of pocket. Then Discovery comes back and refuses to refund me. Even though I have it in writing that Discovery will pay and approved this from my in hospital benefits. Come on Discovery!!!!! Why do you give me written proof plus an authorisation number approving my medication and then refuse to pay me for it!!!!!!!!!!! You guys really disgust me. I get full approval from you from my hospital benefits. Now you say you won't pay as it's take home medicine. Did I take my drip home?????? No. I had it done as you told me to as an out patient in my doctor's rooms- you authorized it!!!!!! Wake up. I want my money back