New service phone is not working

A few weeks ago I switched to your phone service, since then I had to return to the store in Concord, NH since I could not phone anyone. I dial the number and it appears to be calling the person I am try to reach but nothing happens. I also do not received any voicemails and when someone calls me it goes immediately to voicemail and then I don't see any of the VM's. I will be switching two phones back to my original company this can not be resolved easily.  This is an emergency as I have a serious heart issue (leaking mitral valve) and if my doctors can't reach me or I can't reach them it could actually be deadly. I need a quick response, or again I will have to stop your phone service.