Retrieval of share certificate

Hi, Last year I bought used property in kharghar. but also took home loan from private bank. As per rule bank took all the original docs in the custody. Now when I want to transfer share certificate from old owner name to my name. Bank had asked me to submit society letter i.e. the said letter is required from the society for raising retrieval request. When I had approached society they denied this request and told me they never shared society letter to any society members while retrieving share certificate from their respective banks. My bank told me if I am not satisfy with answer or services then contact bank ombudsman. Now please suggest what I suppose to do with this.