I joined Fido a month ago on a 25$ 500mb mobile plan. The agent said there would be an extra 40$ fee to sign up, but he had an offer "tagsraxxx tag" where I would get it back the next month. However, this month the offer has not been applied and it seems at least online support has been closed (just a link to this forum).
These offers often take 2-3 invoices before they apply. How long has it been since you signed up?
That said, our support online is still available. If it's been more than 3 invoices you can check out this page to see all the ways we can be reached, including LiveChat and Social Media.