You should be able to call and ask for it.
If you have TWC phone you'll likely need to be transferred to a different department, but if you don't the rep can probably give it to you. (that's how it works where I live in Ohio).
If you don’t have access to your bill to obtain your Customer Code, you can request your Customer Code by contacting TWC at 1-800-TWC-HELP (1-800-892-4357) and using the keyword "Customer Code". If you have Home Phone service, you can also call 611 directly to request further assistance.
Ref. : http://www.timewarnercable.com/en/residential-home/support/faqs/faqs-account-and-billing/myservices/...
Excellent Surreal! The key is if you have Digital Phone Service with us. If you do not, simple account verification will allow the care agent to provide the Customer Code. If Digital Phone Service is present on the account, the Digital Information Support (DIS) Team will need to complete verification with the customer by contacting them, on their TWC Digital Phone in order to provide the account holder with their Customer Code.