I would take the "you feel that way" out and replace it by:<p>"I'm sorry with our miscommunication, let us refund you your money.  However, we've developed some great premium features that you may be interested in; and of course our the main features are free. Can we convince you otherwise?"<p>"I'm sorry you feel that way" makes it seems that it's the customer's fault and not their fault, it's demeaning to the customer.