cag can I offer a wording for you letter too? My big brother is one of the people who receives letters like this and he says it really helps to keep them polite. He says the person (CEO or whoever) has feelings and will be able to help better if he does not feel personally blamed.
He said try it like this:
Dear CEO,
I wonder if I might ask for your help with a customer service issue your support staff have been unable to resolve? This problem is causing a lot of stress and disruption for my family, and I would be very glad of your assistance.
Briefly, the problem is that I had a large order of furniture booked to arrive on a given day, to coincide with my taking possession of a new house. The delivery has been delayed with minimal communication, and now my flitting is in chaos as a direct consequence. Ideally I would like [insert here what you would like to happen].
If it helps, I can also explain the details of what has gone wrong. [explain details here]
Thank you so much for taking the time to read this. I would really be most grateful for any help that you could give in swiftly correcting the situation.
Yours sincerely.
X