If you have T-Mobile Total Internet Add-on (T-Mobile Internet with Hotspot) you could be paying $29.99 per month for this service. T-Mobile changed the price September 2007 to $19.99 per month, however they negated to let me know so I have been paying an extra $10 per month since sept until now.
The Customer service rep explained to me that they would not lower my payment plan unless I actually called in and asked them.
If you have this service and havent changed to the lower price, you can save $10 per month if you call T-Mobile and have them change your “Total Internet Add-on” to the new tariff — the customer service number is 1800-937-8997
Alternately you can also change the plan by going to https://my.t-mobile.com/login/? entering your login details, click on the “Plans and Services” tab, click “add or change services” and select “T-Mobile Total Internet Add-on”
This $10 is better off in your pocket rather than T-Mobiles.