Bank not providing copy of sales deed

I have taken home loan from one of the major bank before two months. Registration was completed before one and half months. The property which I bought had a loan with another bank and part of the disbursed loan amount was send to this bank for closing the previous loan which was in seller's name. The problem that I am currently facing is that bank is not providing the copy of registration document which I require for the mutation of property. Registration document was prepared by bank's lawyer and lawyer's representative was present during the registration of the property. The entire process of registration was done successfully (I assumed that the registration document was taken by bank's representative). When I asked bank, they are saying that the delay is normal and they have not received documents from lawyer's office. After repeated queries, they are saying that they have not received the document from registration office and it is at registration office for some reason. 1. Is this delay normal? 2. What's reason behind this delay at registration office? 3. Is this because seller has not completely closed the previous loan by paying his dues? 4. What should I do next?