"Forgot to send me a follow up appointment"

After having an appointment with a doctor they told me to make an appointment with the receptionist for the treatment on the lump on my gum. The receptionist told me they cold not make an appointment and I would get a letter in the post. Two weeks later I had not received a letter so decided to call them to see what happened. There was no follow up app. on the system and someone would call me back, two days later and no one had called. Since then I have been trying to get in touch but nobody answers the phone. So what do I do now ?