Shop divided into two

Ok so a little background the shop that i bought last year has two parts part A (500 sgft) and part B (100 sqft) currently seperated by a wall. Both having seperate agreements but marketed and sold as one by the builder. Now since i did not have adequate funds i bought part A from the previous owner on verbal assurance that he will ensure that i face no issues in registering my part of the shop. I was able to easily get the same registered with the registrar pay stamduty and get it transferred to my name on government records. However the society has now refused to transfer the property on my name as according to them both the parts go hand in hand. The previous owner has gone back on his word and although he is still using part B of the property i am forced to pay the maintenance for the entire property by the society . Further buying the other part from him is currently beyond my capacity and also since my shop papers are not clear i am unable to get a loan or od for business purposes.