greeting
Dear Sir/Madam,
introducing your reason for writing
I am writing to express my dissatisfaction at the service I received.
background information
I have been a regular customer of your shop for many years.
what went wrong
After leaving your shop today, I realised I had been charged £100 instead of £10.
what you'd like to happen
I would like a refund of the difference as soon as possible.
closing
Yours faithfully,
https://339efcb25eb75e967b0d-ff8eeadd950d51fd1fc939dca75b3973.ssl.cf1.rackcdn.com/assets_default.swf