What if someone does not pay the full amount of biyana??

Dear masters,
I have a query.
I sold my house in august with a time limit of full payment after 6 months and bayana of 70 lac in august as per written agreement.The buyer gave me 20 lac on the spot and said that he will pay the rest in some days but nov has come and he didn't pay the remaining amount of bayana.Any legal suggestions that is the agreement cancelled and his 20 lac is non returnable or i have to pay him back 20 lac if i send ho legal notice and cancel the contract???

.

.

.

Waqas sb,

It all depends upon the contents and clauses in the written agreement between both the parties.

Regards