Contesting it depends on whether she signed a new contract. If she did, you need to demand a copy of it and if it can't be produced you're home free.

If it was a verbal contract made with a call center, you have to demand a tape of the conversation. If it can't be produced again, you're home free.

Don't misunderstand my home free statements. You will likely spend hours talking to multiple supervisors who will tell you no over and over again. You have to be polite but firm.

If they do produce a written document or recorded call it becomes nearly impossible to get out of unless there was a change in terms to the contract that you didn't agree to.