Dear valued client

Further to your recent voicemail message, I am writing to inform you that we are unable to credit the invoice in dispute. Furthermore, I must regretfully decline your request to roll up and insert the document in question up my arse.

While I appreciate your frustration relating to this outstanding matter I am, due to current work commitments, unable to fu#k off. However, as a gesture of goodwill, I will re-issue your invoice, with a 15% surcharge, and place your account into collection.

Once again, let me sincerely apologise for introducing you to reality. You are a valued client of ours and over the years we have established an honest and transparent business relationship....so you won't mind me telling you that I think you are a cock.

Yours sincerely
Account Director