You can try asking HDFC customer support for converting your DCB to LTF under Alumni offer, if you are an alumni of any of the colleges below
1) IIM Calcutta
2) FMS Delhi
3) Jamnalal Bajaj(JBIMS)
4) IIM Bangalore
5) IIM Lucknow
6) IIM Ahmedabad
7) MDI Gurgaon
8)IIFT Delhi & Kol
9) SP Jain...