"No one answers the phone or returns calls"

I am currently under the care of the dermatology department. Due to the nature of the medication i take, I am supposed to be seen in clinic every 4 weeks and am then given my next prescription for the following 4 weeks. I was advised by the doctor to never run out of medication. I spent everyday last week trying to get hold of someone in the dermatology department. I left countless messages with various receptionists, explaining that I will run out of tablets vey soon, but no one has had the decency to return my call. It is now Monday and I will run out of tablets in a couple of days time. I am extremely disappointed with the lack of service, and have found the entire experience very stressful. I fear my only option now is to turn up at the clinic unannounced this week in the hopes that one of the doctors may see me without an appointment. The lack of care is truely astonishing.