T-Mobile T-mobile extended contract on two existing month to month phone lines against verbal agreement , Internet

I had two phone lines with t-mobile wireless on month to month contracts. In the course of adding a third line under contract, I had explictly asked the salesman to make sure that the third line would not change the contracts for the existing phones.

a year and half  of service later, I decided to terminate the two monthly contracts and move to another company. T-mobile is now charging me 200 + 200 early termination fees stating breach of contract.

When I called, I was told, as part of the addition of the third line, the plan was changed which included a contract. I mentioned my interaction with the store based employee who had explictly told me there would be no changes to the previous phones in the account. They said, you signed a contrct and should have read the fine print. Does a verbal contract not hold any promise anymore?

what should I do.