(1) the appeal is filed more than 90 days after the certified mailing to the tenant of the initial apartment registration, together with the notice pursuant to section 2523.1 of this Title; or
(2) the appeal is filed more than four years after the vacancy which caused the housing accommodation to no longer be subject to the City Rent Law.
(d)
(1) The order shall direct the affected owner to make the refund of any excess rent to the tenant in cash, check or money order, and to the extent the present owner is liable for all or any part of the refund, such present owner may credit such refund against future rents over a period not in excess of six months. In the absence of collusion between the present owner and any prior owner, where no records sufficient to establish the fair market rent were provided at a judicial sale, or such other sale effected in connection with, or to resolve, in whole or in part, a bankruptcy proceeding, mortgage foreclosure action or other judicial proceeding, an owner who purchases upon or subsequent to such sale shall not be liable for excess rent collected by any owner prior to such sale. An owner who did not purchase at such sale, but who purchased subsequent to such sale shall also not be liable for excess rent collected by any prior owner subsequent to such sale to the extent that such excess rent is the result of excess rent collected prior to such sale. If the refund exceeds the total rent due for six months, the tenant at his or her option may continue to abate his or her rent until the refund is fully credited, or request the present owner to refund any balance outstanding at the end of such six-month period.