Insulin pen needles not covered by medical aid rendering the device useless

After a lot of "mistakes" by Discovery and no further progress on getting the right medication for diabetes I have been placed on insulin by the Drs. Discovery is paying for the insulin that is called cartridges that is placed in a pen. The pen and cartridges they paid for, however the needles that goes with the pen, they refuse to pay for. Why I may ask, without the needles the pen and cartridges are useless. Maybe the expecting me to lick it up. Disgusting medical aid, always excuses not to pay. It's not about your health but about their profit margins.