Welcome to the community!
I understand you live in Ontario. Do you also have an Ontario phone number? The billing taxes would follow the Province from which your phone number belongs, not necessarily the Province in which you reside. For example, if your phone number was originally from NB, you would be charged NB's HST of 15% even though you live in ON.
That said, even with the higher HST, the total would be less than $70. Have you had a chance to view the details of your bill via My Account? Is it possible there are additional charges for that billing cycle?
Hope this helps 😀