Bank of America does not honor Countrywide's original terms forcing me to pay 3 times more per month

I got a Countrywide Home Equity Loan back in March of 2007.  The terms were that the first 5 years was the drawdown period, then the next five years was payback period using interest only calculation, then after that was supposed to be a 15 yr amortizing payback period.  Well now that Bank of America had purchased Countrywide, they are stating that they do not honor the original terms and they have stepped up the 15 amortizing period bypassing the my 5 year interest only period.  The amortizing monthly payments are 3 times as much as what the interest only payments are.   Can Bank of America do that?  What recourse do I have and who can help me fight this.