Should I create a new account to take the questionnaire again or because I had an issue when completing the questionnaire?
Under no conditions should you create a new account in the system. The system is designed to identify duplicates accounts and when found, it locks the accounts and marks them as a Violation of the T&C's. This will prevent your result from being available to the company that asked you to complete the process.
If you are having issues, you should use the contact form found on the registration page for assistance.