I followed your link- and took the steps- and at the end it gave me a pop up window that said "contact customer support" to cancel.
When I clicked on that it started the same circular process again.
the final screen from customer support says something like "if you have signed in (which I have) select phone or chat below"- but there is no place where phone or chat appears as a choice.
Is it really this hard????
Your Stock plan has been cancelled and will not renew next month.