Dispute over verbal agreement for shop ownership

I rented a shop for 30 years from a family who inherited the property. One brother verbally agreed to transfer ownership to you after 10 years of gradual payments, but this was not written down. Now, he claims he can't fulfill the promise since the shop isn't in his name. He's offering documents acknowledging receipt of money from you, but these documents don't serve as collateral for the property or guarantee repayment. Essentially, he's admitting to receiving money from you But not repaying