They'll do anything for sales!!!

How do you sell someone a product and not tell them about the extra charges they have to pay? I only found out when I got my statement for this month that I was supposed to pay pro-rata charges when I got the Wi-Fi. It's such a huge inconvenience because we budget for these things and they just decide to do as they please as if money grows from trees!!! Mtn do better and communicate with your customers prior about such thing!