A transaction which does not satisfy one or more of the requirements of s. 706.02 may be enforceable in whole or in part under doctrines of equity, provided all of the elements of the transaction are clearly and satisfactorily proved and, in addition:

   (1)   The deficiency of the conveyance may be supplied by reformation in equity; or

   (2)   The party against whom enforcement is sought would be unjustly enriched if enforcement of the transaction were denied; or

   (3)   The party against whom enforcement is sought is equitably estopped from asserting the deficiency. A party may be so estopped whenever, pursuant to the transaction and in good faith reliance thereon, the party claiming estoppel has changed his or her position to the party’s substantial detriment under circumstances such that the detriment so incurred may not be effectively recovered otherwise than by enforcement of the transaction, and either:

      (a)    The grantee has been admitted into substantial possession or use of the premises or has been permitted to retain such possession or use after termination of a prior right thereto; or

      (b)    The detriment so incurred was incurred with the prior knowing consent or approval of the party sought to be estopped.