Is photocopy of allotment letter enough for deed registration?

I started living in a flat in 2004 and made a confirmation deed, power of attorney (POA), and memorandum of understanding (MOU), and continued the existing bank loan that was originally in the name of the first owner. In 2011, I registered the confirmation deed and paid the necessary stamp duty, though I only had a photocopy of the original allotment letter, as the original was with the bank. In 2018, I fully paid off the loan. However, when I applied for society membership, the society rejected my application, claiming that the confirmation deed is invalid. They allege that since the original allotment letter was not attached at the time of registration, I committed forgery. The seller and the bank have never raised any issue. My question is: Does submitting a photocopy of the allotment letter, instead of the original, at the time of registration constitute fraud? What is the legal solution to this?