Architect Letter

Hi. This is Shraddha, my husband n me hv purchased a under construction flat in Naigaon Mumbai.for which 20% payment is done, and rest 80% will be going by Home loan, our registration was done in Feb 2015, initially the builder was asking us to process the loan from Indiabulls as the property is approved by them but we processed the same with Axis and it is sanctioned but after submitting the documents (even original sales Agreement) the builder refused to provide architect letter of Construction at last moment hence the Disburstment was kept on hold by Axis and builder again asked us to go with indiabulls and just to save time we processed it with Indiabulls and it is now declined by indiabulls as my husband is self employed and the income do not match for the amount we need, now the builder is saying if we do not pay the remaining balance within a month then they will charge us the interest, just wanted to check that how important is Architect letter for Loan Disbursment. And do we have any source incase we do not get the document from builder. Looking forward for your advice Best Regards Shraddha