I need some advice. T-Mobile refuses to cancel my service because they falsely claim I agreed to a contract extension over the phone. I tried explaining that I never agreed to an extension but couldn't get anywhere with them. What can I do? Are over-the-phone contracts even valid? What safeguard does a customer have against someone at T-Mobile (purposely/mistakenly) putting them on a contract over the phone? Is the $400 charge worth taking legal action?