I got the fido sim back in september and the bill they charged me was 114 CAD. I paid something like 80.63 CAD because it was showing only that amount in my fido app at that time. But now I got the mail that I have to pay 128 CAD while my app shows me 47 CAD.
Welcome to the community!
You can save/print your invoice details (see here for how to do that) and it will tell you what you are being charged for.
Depending on how you made your payment it could not have been reflected at the time you got the email, if you are still unsure of the numbers I would suggest you contact customer service directly and they can better assist you.