To cancel auto renew for your Ecommerce package, please do the following:
Log in to your 123-reg control panel.
Scroll down to the Ecommerce section.
Click on the Manage ecommerce plans option.
If you have more than one ecommerce package, click on the Manage button for the relevant package.
Click on the Manual renew button next to the Auto renew: option and click on the change button.