How to get a no objection certificate from LICHFL to swap a flat

I have taken a Home loan from LIC HFL to buy a flat. The flat initially that was alloted to me was 15th floor. The flat is a 19 floor building and is expected to get completed by February 2018. The flat is been constructed by TNHB(Tamilnadu Housing board) and the 15th floor of the flat has been alloted to me by TNHB. All the loan proceedings against LICHFL is been processed by the initial allotment of 15thfloor. Meanwhile I gave a requisition letter to TNHB to make an allotment to the 5th floor instead of the 15th floor. To make this allotment the authorities of TNHB is requesting for a NOC(No objection certificate) from the LICHFL authorities to make the allotement to the 5 th floor. When approached LIC HFL for the No Objection certificate, the authorities denied to give the NOC stating that swapping of the flat is not possible. And the written request to the customer support team also is still unanswered. Can you please provide a legal opinion to get the NOC from LICHFL?