Dear Sir

When I attempted to utilize my ___________________ (name of the firm) charge card for a purchase on ___________ (date), I was informed that I would have to speak to the credit office before I could charge any additional purchases to my account. As there were several customers waiting in line in your credit office, I am writing to you instead.

Could you please tell me if there is a problem with my account, and, if so, the nature of the problem?

I will be looking forward to your prompt reply.