Dear Sir or Madam,
I am writing this letter to express my disappointment in the service  I received during my meal last night at at your restaurant. I would like to make a complaint against the bad service received.
I  went the restaurant to celebrate one of my friend’s birthday. After getting a table we had to wait for almost an hour for the waiter to come and take our order, and beyond that, he seemed hesitant to take our order. We had to wait for half an hour after placing the order. The food was cold and I even found a hair in my food. The waiter was very impolite to us after we told him the problems.
I request you to look into matter and take some action against the waiter or else you  will lose some of your loyal customers.
Regards,
sans.