Kindly clarify whether mortgage is registered or not .?if property was mortgaged finance company should have been given original documents of tile
2)your agreement with seller was unregistered
3) the subsequent mortgage in favour of AU finance was illegal
4) you should file case of cheating , criminal breach of trust against seller under section 406, 420 of IPC
5) you can file suit of specific performance against seller to execute registered sale deed in your favour
6) bank would seek to auction the property
7) you have to file application before DRT seek stay of auction