From my experience with Visa Debit cards where I work, the mailing address for the bank account and the address on file with the merchant (ie Telus) has to match exactly or the transaction fails. It may be the same issue here.
PayPal is an American payment company. It is fully unregulated, uninsured (ie FDIC/CDIC), and there have been tons of horror stories over the years of problems people had with PayPal. Plus PayPal has it's own fees for both merchants and end users. People are unhappy with the 1.75% fee for cards here now but PayPal charges more. (2.90% + their fixed fee.)
I just make a deferred payment through my online banking as soon as I review the bill. Takes no more effort than paying with a card. I could have set up automatic debit, but this method forces me to review the bill.