you could provide more information about the make and model of the phone, but I don't think it matters. I sounds like that phone is defective.
it could be defective software so try a full reset before giving up on it.
you SHOULD be able to take a defective set back to the store you bought it at and get a full, new replacement HOWEVER what will probably happen is, the Fido store will imply that you may have damaged it and it will have to go back to the manufacturer to get evaluated and repaired.
No, you likely won't get a replacement phone right away or get a loaner phone because Fido wipes their hands of any responsibility for selling you a defective set. Somebody else's fault.
I noticed you have an iPhone since you posted in the iPhone section. There is hope for you and its actually a lot easier than what oblaP claims. Simply take your Apple iPhone, regardless if its a 3G, 3GS or 4 to the nearest Apple Store to you, and simply just give it to the Apple Genius counter. They will fix or replace your apple iPhone for you within the warranty period.
Some things you might want to try BEFORE you take it to Apple, try a Full factory Reset, and check to see if an Updated Software exists for your phone model, this might solve it without the need to take it to apple, but if it doesn't, then you can take it to apple.
Hope This Helps.