This Neighbourhood is inhabited by customers, just like you. We have no insight to Telus business plans, and no connection to the internal workings of Telus. We volunteer to share knowledge about Telus products and services which we have gained by experience or surmise. No one here has the ability to make changes to your account.
How much are you over? The first 50 GB is only $5. You can also upgrade to unlimited online through My Account, or connect with Telus staff directly through a phone call, chat, Facebook or Twitter, as described in the Contact Us section at the bottom of the page.
If you wish to add unlimited data, note that it will go into effect after you enable it. Meaning that you will have to pay overage - likely $5 - plus the $15 for unlimited. I would advise you to wait till the beginning of your new billing cycle and then add the unlimited Internet and pay the overage for now.