The seller not adhering to agreement terms

if you have done with your part of the agreement and the other party is refusing to perform their part then you can send them a notice to perform their part failing which you can file a suit for specific performance

You are silent on terms of reference with regards to cancellation of contract mid way through. If the contract is silent you can take a call as per above counsel views, if it has you have to go by that. My opinion is, not to deal with such persons who keeps changing minds frequently, get back the money( along with interest) go for some other property.

Thanks for the valuable replies..

The terms of reference as follows

1. If the seller default to execute the deal within the agreemnt period the buyer can approach a competant court to register the deed by paying the balance amount

2. If the buyer default to execute seller have to return the advance amount deducting 10 % as penalty..

My advance agreemnet in 500 Rs paper and not registered. 

Still terms of reference are not clear, but still as per contractual obligations, if you are ready with the money and same has been expressed by notice to the concerned parties (sellers) and their constant refusal to fulfill contractual obligations, may invite court to interfere, on the other hand if you are not ready to carry on with this, you can opt for second point , collect you money back  without any deductions , if possible along with interest.

Will court accept my un registered advance agreement if I proceed for filing a case

If the suit is initiated within the time frame mentioned in agreement, the court will take it up.

I want to go with the case but many of my friends including the deed registration agents warn me that I will not get a favourable verdit since my advance agreement is not registered with registration dept.

I do not want to comment on others views, i stick to my  views , it is up to you accept or reject the same.

thank you sir