Negligence and incompetence - medication not delivered and no feedback

I have been following-up on my medication since last week and everytime I phone I am told that Maureen who is the one responsible will get back to me. I believe she has her own managers senior to her but they are not intervening. I informed them last week that I am on my last 4 tablets and that is finished. They made a mistake and thought they dispatched a 3 months supply of which they never did. Their service is becoming very sluggish lately. Every month I have to phone them for my medication and all the time it has to be delivered as an emergency and I end up losing on the previous month supply. The Team Leaders have become so *********** and careless. My life depends on this medication.