Property issue from seller

We decided to buy property of 73 lakhs in my mother name but after giving token advance seller took time and refused to sell property but again he wanted to rise the price and he demanded for more we agreed for 74lakhs and gave advance of 8 lakhs and made sale agreement later again he started refusing to sell the property. Then we already paid for agreement and broker and also loan processing we said we'll sell this to someone if you want more but he refused and said he will return the money before 3 months but he took 3 months time and without telling us my mother and seller spoke and they decided and seller transferred to her account only 8 lakhs but i and my husband decided to buy we invested but due to loan process we decided to take in her name we took care of all the expenses he only returned (8lakhs) what we gave. Shouldn't he should give 5 % ?? And also original sale agreement is with us he still haven't collected but he already transferred please please suggest what we can do in this case