Betterment charges receipt paid to cmc

Hi I have purchased BBMP A khata site during 2012and it was under CMC and betterment charges has been paid to CMC to convert it into A Khata. Now BBMP asking for  betterment charges with new rate and  they are asking for receipt if you have paid before adding to BBMP. But I don't have any receipt for betterment charges paid to CMC, please advise how to get receipt for betterment charges paid to CMC or anyother alternative ?