Incorrect nominee name and subsequent transfer to legal heir

Sir/Madam, Upon the death of my mother, I being the only child of my parents, I found that among the FDs in her name in the bank, a few which totals to a considerable amount are under the name of an non-existent individual. The relationship mentioned therein is 'daughter' and it has to be only me. In the nominee register of that year of making FD, only the first name of the said non-existent person has been written down. While typing in the computer, they added my surname to that name. I did not know this since it was done around the time of my father's passing away. I believe, this discrepancy shows its the bank's mistake, since every other dealing with the bank is only my dad, my mom and I. They are unable to find the original nomination paper. Now, I am being asked to provide a Succession Certificate which I know will take months on end. Please guide me as to how I should approach it. There is no will left behind. Ration Card has only the 3 of us. No one in my family goes with the name that is mentioned in the FD as nominee. They say that a family tree is no good in this regard. But the same was accepted elsewhere. I am afraid that I am being made to run around for no fault of mine (that's what I presume).