2. Express your concern over the writer's troubles and your appreciation that he has written you.
3. If you deny the request, explain the reasons why the request cannot be granted in as cordial and non-combative manner as possible. If you grant the request, don't sound as if you are doing so in a begrudging way.
4. If you deny the request, try to offer some partial or substitute compensation or offer some friendly advice (to take the sting out of the denial).
5. Conclude the letter cordially, perhaps expressing confidence that you and the writer will continue doing business.