What happens when you go over your data plan?

I'm with telus and have an iphone 4s. I have a certain amout of gigabites of 3G and i know i went over. I went to my grandparents and they don't have internet so i used 3G for everything, does telus charge you for going over your limit?

With pretty much any phone plan, you do get charged for going over the limit and usually it is quite a substantial amount. How much specifically depends on the phone carrier and how much over.

Best way to check that is by calling customer services. Or you can check on their website if they have the option of checking out of bundle charges. But mostly customer services option helps cause they can check every detailed info.