Have you never logged in to your account to see usage, what plan you are on, billing info, etc? You should have created a Self Serve account right when your account was created though I have heard of some activations at dealers getting you working but not instructing you to create the Self Serve account. You would have received a text message with PIN code I believe at activation to set up the Self Serve. If you have Autopay set up I think you can dial 611 to buy add-on, check balance etc. This means you could have done this at the cottage.
@Corwin If you got a warning then more than likely you have used up your data.
You can purchase a data add-on or submit a ticket to PM and ask them to renew your plan early.
Make sure that the start dates on your device and plan are the same as far as data usage goes.