If the promoter,-
(a) fails to give possession, in accordance with the terms of his agreement, of a plot or an apartment duly completed by the date specified, or any further date agreed to by the parties; or
(b) for reasons beyond his control and of his agents, is unable to give possession of the plot or the apartment by the date specified, or the further agreed date; the promoter shall be liable on demand, but without prejudice to any other remedies to which he may be liable, to refund the amounts already received by him in respect of that plot or apartments with simple interest at the rate as may be determined by the competent authority from the date the promoter received the sums till the date the amounts and interest thereon is refunded, and the amounts and the interest shall be a charge on the land on which a plot it to be developed, or a building is or was to be constructed and the construction, if any, thereon shall be subject to any prior encumbrances.