I have partially signed up for Taobao, but did not complete the process. I now have a problem as my email, phone number are now recognized as being registered to an account. I cannot even create a new account.

Any useful advice or assistance please.

I think your best option is to contact Taobao itself and ask for help to continue your signup

I had a similar problem before. I think I found a "forgot your password" option and they email a new password. Then can continue setting up the account.