Title of purchaser not to be impeached on the ground of irregularity, etc.

21. When a sale has been made in professed exercise of a power of sale under section 13 and has been confirmed under sub-section

1. (3) of section 15, the title of the purchaser shall not be impeachable on the ground that no case had arisen to authorize the sale or that due notice was not given or that the power was otherwise improperly or irregularly exercised but any person damnified by an unauthorized or improper or irregular exercise of the power shall have his remedy in damages against the primary land development bank.