If you are not using this SIM card anymore, you should go contact a moderator or contact with Fido Solutions on Twitter and Facebook messager. https://twitter.com/FidoSolutions or https://fb.com/msg/fidomobile. The 3-month bill that you already paid is nonrefundable. In order to avoid the next bill cycle's autopayment, you should contact them ASAP and cancel your service. Otherwise, the billing cycle will carry on and you will probably lose credit if you didn't pay for the bill.