Shame on you

After many emails between myself & Virgin, we decided under deress to pay the amount outstanding (according to them) on the 13th of December. So that my credit record is not affected negatively. On the 22nd of December we emailed them requesting a letter stating this account is paid up and no amount is outstanding. We did not hear form them at all, then on the 5th of January we send another email requesting this letter. Again NO RESPONSE from VIRGIN. Why can they not respond to emails and send the letter stating the contract is paid up? This surely indicates that something is not right. Are they not working above board with the contracts.