Aditya birla finance home loan issue

I had taken a home loan from ABHL, in Nov 2017 for 80l, @ 8.5% floating, all my EMI'S Have been paid on time till date, Now within yr, ABHL had increased the ROI 4times, and now my current rate is 9.52%, Now because of this increase i decided to do a BT, which i got @ 8.5%, but when i asked for foreclosure letter to ABHL, they gave me with FC CHARGES @ 2% on outstanding, when i approached them for clarification they told that they have charged as per the sanction letter. When i reffered the sanction letter it read as NIL pre-payment charges for individuals, and 2% FC for non-individuals for foreclosing within 3yrs. I again approached them with the letter,and told that i am individual, hence FC charges don,t apply, on thatthey said that i am non-individual, due to my firm (a proprietory concern) also being a co-borrower in the aforesaid loan, now this was very new to me, till date i beleived as per incometax dept that a proprietory firm and individaul are the same, i tried to argue with them, but they showed me an NHB circular and sanction letter. Now as per this circular i had become a non-individual , but this circular was never ever disclosed to me at the time of loan sanction, what action can i take against ABFL..?, PLEASE GUIDE...