How to Lose a Customer

I had a regular check-up booked with my (former) dentist in November. With my whooping cough, I had to cancel that. I explained that it would be *months* before I could lie back with someone poking about in my mouth without coughing myself in to unconsciousness or vomiting. They have continued to nag me about my appointment and I explained again and again and AGAIN the nature of this disease and that I would contact them when I was well enough to tolerate a cleaning without a paroxysmal coughing fit. So today, after receiving yet another nag by e-mail (rife with cringe-worthy grammar and syntax) this was my reply:

I have explained no less than three times now that I have had a serious illness. I'm disinclined to explain this again or ask again that you wait until I contact you when I am physically capable of tolerating a dental appointment. 

Do not contact me again. I will not be coming back to your office.