Hello Shirerey,
Welcome to the community!
While there are some promotions which are only for new activations or hardware upgrades, I don't think that is the case in your situaiton. If your contract is ending in September, it's likely your plan is under the subsidised model. With the subsidised plan model, the cost of devices was incorporated into the cost of plans (ie Small, Medium, Large, etc). You should note that Fido has recently switched from their old subsidy model to a financed Payment Program. With the new model, the cost of devices is separate from the cost of plans. Since the costs are separate, you would no longer have a monthly finance charge once you have paid-off the balance of the phone.
Plans under the old subsidised model are not compatible with the new financed model. I believe if you are researching options with a subsidised plan, the system won't properly show the new plan options.
If you would like to pay the remaining device balance, you would need to contact customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above. Once you have paid the balance of your device, you could have customer service switch your plan to a new one.
Hope this helps 😀
Cheers
