Problem opening an new account with cellc

I'm lodging an complaint about Cell C.. Yesterday I wanted to open a new contract with Cell C, they told me that I cant open an new Contract because I have been Blacklisted for non payment. I have made a payment with FNB for the amount of R706.00 for the amount outstanding and send a copy of payment to D. Mangeni on the 8 May 2015. All other payment then was taken via debit order.