The Castenholz case held that subsection (7) penalties are appropriate even when the tenant remains in possession where a landlord fails to establish a separate account as required by subsection 3 (a) and refuses to return the deposit on demand, thus forcing the tenant to litigate. Castenholz, 21 Mass. App. Ct. at 764. Patukonis maintains that because of the violation of the security deposit law she was forced to litigate in order to vindicate her rights. Since Young failed to place the security deposit in a separate account within thirty days after receiving it, he was obliged to return the deposit on demand. See § 15B (3) (a) & 6 (a). Patukonis made the demand for the return of her security deposit in her counterclaim (December, 1983) to the first of the three summary process actions. See Castenholz, 21 Mass. App. Ct. at 764. Young did not acknowledge his error nor did he promptly tender the deposit; five months passed before the deposit was returned. During that five-month period, the tenant, in her counterclaim to the second summary process action, again made demand for the return of her security deposit. We thus agree with the tenant that subsection (7) is applicable to these circumstances and, accordingly, that Young is liable for treble damages, interest, costs, and attorney’s fees. C. Boston Rent Control Ordinance Violation.