DMC does not want to send a paid up letter!

Very annoyed with DMC firstly their website states that we can use our ID as a reference number and after I paid they do not want to give me a paid up letter. They first said that they sent my paid up letter to the incorrect address and then after they asked me to send proof of payment of which I have done twice. They still have not sent me my paid up letter and now say it will take 4-7 days. How can a piece of paper take 4-7 days to reach a client? They are sending it via email and not airmail. I am very frustrated with the arrogance of their consultants as well.