Hello ChoKen,
Welcome to the community!
Firstly, you should note that the expiry date for the $50 vouchers is not half that of the $100 vouchers (see here). In addition, the voucher expiry dates are not cumulative. That is, the purchase and activation of two $50 vouchers would extend the expiry date by 60 days, not 120 days. Furthermore, the expiry date would follow the most recent voucher activation. For example, an activation of a voucher with 60 days expiry followed by the activation of a 30 day expiry voucher would result in your funds expiring in 30 days.
I understand your grocery store only offers the $50 vouchers. You may be able to avail of a higher denomination by topping up through Fido (see here).
Hope this helps 😀
Cheers
