T - Mobile Forcing me to pay the cell phone usage charges whom i have nothing to do with Internet

I have been a T-mobile loyal customer since 2007. I never had an excellent cell phone service but still i never complaint to T-Mobile and continued my service as that what suited my pocket best. Even though i faced regular dropped calls and dead slow wireless Internet availability on my cell phones i still never thought of switching up until now. I added a new line to my wireless service last month and signed up for T-mobile unlimited talk plan for 49.99$ a month with no sms and data package. My normal cell phone bill is 100$ a month and adding this line would have added it up to 160 -170 a month including all the taxes but T-Mobile end up sending me a cell phone bill for 618$ approx for last month. When i asked why i was send such a huge bill they replied i made 400$ worth of international calls from my new cell phone line. First i dont understand how come a cell phone can make an international call without any notification or restriction. Second i never made those calls and when i tried to file a complaint to the representative they wont take my complaint. They even added 120$ more to current month bill. They totally ripped me of for something i have nothing to do with and also threatened me if i dont pay my bills i have to face the consequences. Why should i pay 520$ for something i didnt even do. My money is not money. I am filing this complain because i dont want this to happened with other people as it happened with me. My suggestion is please stay away from T-mobile, as they really know how to rip you off legally. Right now i have no choice expect to pay that bill as if i dont my credit history will be spoiled. Filing a lawsuit against these people will also be useless as its just 520 $ and no one will help me with that. I will just say please do not buy T-mobile Cell phones. Please do not T-mobile as a wireless provider. If you ignore this warning you might end up paying 10-20 times more than your bill lately.