My Site has been blocked even though no invoice is due!

Today is th 4th April and the new invoice just came out which reflects due on the 16th, but my site has been blocked regardless. 

How can i get it unblocked asap because even if i make an earlier payment than necessary to you, it will still take almost a week for you to get the payment and unblock it. This is unacceptable as the error is with you and not with us.