I am retired Canadian citizen with only pension and supplement income and no credit rating, that is why I am constantly refused to getting (receiving a credit card) from wherever I have tried to get one. So I deal only in cash and direct payments.

Are you a prepaid or postpaid customer?

if you don't have credit card, you could use your online banking to pay. Alternatively, you could visit a Koodo kiosk and pay there. 

Stores that sell vouchers

https://www.koodomobile.com/prepaid-vouchers

Since you are on a prepaid plan, you don’t have to go directly to a bank. Other than registering your credit card or Visa debit card on your Self-Serve account, you can buy top-up vouchers or top-up instantly at your nearest Koodo store or various stores across Canada. For more information, visit this link. https://www.koodomobile.com/en/help/topping-your-prepaid-account