Oversatisfied Costumer

I have mentioned here about my dental check up last month right? As far as I remember, I also mention how satisfied I was about their dental job. They cleaned my teeth so well, and replace the fillings I had on four of my tooth. My insurance company cover only 50% of the total expenses, so I paid half of it. Last week the secretary of my dentist called me and informed about the money their going to send for me because they charge overpay. Today, I received an envelop in my mailbox and sure enough its their check payable for me. I am really happy because they are so nice and honest to return my moneys back even though I have no idea how they calculate the price of their services rendered for me. Because of that I am so sure to go back them if I need a dental check up next time.