Do I have to pay?

On 8/14/07 I called Earthlink to cancel my e-mail account with them. I spoke to someone there who took my information and he gave me a confirmation # of 13069074.

In Sept. of 07 I received a bill from Bill Me Later of $21.00. I mailed a denial of payment along with my confirmation number. In November I received a letter stating that Eatthlink had denied that I ever canceled. I was told that I must pay the bill. I called Earthlink and was told that I had never called to cancel and that there was no such confirmation number and that I must pay the bill.