If a company sells a contract to another company and the contract was ending around the time they assumed the contract, is that still honored?

My mother signed a loan repayment agreement with Beneficial Mortgage Co. of South Carolina back in June 20, 2000. They initially had her account set up to pay back monthly for 30 years unless she elected the EZ pay option of bi-weekly payments which would reduce her paying to 17 years. When the company sold the agreement to Equity One who eventually sold it to Fay Servicing Inc, now Fay Servicing says that my mom has to pay the rest of the 30 year she agreed to when the company is still pulling out ACH drafts every two weeks. Is there anything my mother can do where the original contract is still honored and her debt be considered "paid in full" after 2017?