Getting Banned. Help needed!

Recently I received an email from CodeChef informing me that multiple accounts are being run on my email ID. But as per my knowledge, I have used only one account since the beginning.

I was told to delete them before 16 Feb else my account will be deleted forever.

How should I fix this problem. Can I get the usernames of the accounts being run on my email, if they exists, so that I can delete them?

P.S: I have mailed CodeChef twice regarding the same but have received no response yet.

refer this: "Multiple CodeChef accounts associated with this email address"?


Thank you so much.
May be this is a bug.