Breach of Contract?

Breach of Contract?
We are selling a car and the person that test drove it, crashed it. After some pushing by us he decided to purchase the vehicle instead of paying for the damage. He was aware that the registration was due on the vehicle and initially agreed to pay it. We all signed the DMV papers for the full purchase amount but he brought the check for the price less the registration stating that WE are responisible for it. That was not the deal. We refused to budge and he left. Didnt he breach the contract since he signed the Bill of Sale for the full amount but failed to comply? And for our info, does it matter who pays the registration?

mis use of general power of attorney i had given a general power of attorney…

mis use of general power of attorney
i had given a general power of attorney (registered) to two agents- my father and brother in 1982 .the GPOA had all kinds of powers given to them. I was in CRPF at various places till 2007 when i was retired and came home. i had about 5 acre of land on my name when i had made this GPOA. my agents bought a few more land on my name with my GPOA. but when i came back i found that my father (one agent ) had shown my 5 acre land portion (2 acre ) to my brother (another agent of my GPOA ) as sold and made sale deeds using my GPOA.this land sold was on the road side and completely blocking my land from main road thus even reduced the value. since then i got my GPOA revoked. now they have turned against me.
1. is it correct legally for my agents to transfer land between them showing as sale deed using my GPOA.?
2.is it not a breach of trust as they were to act for me and on my behalf. can they function against me..?
3. under what ipc the charges can be framed… is it a criminal case or civil..?what should be my line of argument in the court..?