I've been trying for 12+ hours to change my plan via self-service on Fido.ca to take advantage of the $60/10GB plan.
Have followed the instructions you posted on twitter (https://t.co/HrypsS6A4Z), and done all the requisite trouble shooting (clear cache, cookies, history, different browsers, etc...) with no success. It's been nothing but "This is embarrasing" and "Oops something went wrong."
Unfortunately, the fido social media team doesn't seem to be aware of this issue yet so they're still directing everybody to the instructions...that don't work. Any help or update would be greatly appreciated.