"Difficult to contact"

I received a letter recently dated mid Aug advising that numerous attempts had been made to contact me regarding areas of basal cell carcinoma I had treated several years ago. I could not respond to these calls as no return number was left on the messages and the number it came from did not take incoming calls, I suggest that a contactable number is left with these messages as I would have certainly called back.

I am also unsure of the reason for these calls as I attended the clinic June of this year and had a full skin check at the time. I can only assume it is because I called for some advice back in March, left a message and no one had  returned my call.