DMC refusing to give me paid up letter

I Paid my account via dmc on their website. When I demand my paid up letter they keep on saying I used a wrong reference number and I should wait for 7 days. They asked me to wait for 7 days twice and this is unacceptable. I need my paid up letter now! Today even worse Ayabonga cut our conversation when I told her/him that I did use the correct reference