By a “letter of compliance” do you mean a “notice to comply” (NTC) provided on the approved form? If so, the next step is to take them to NCAT for fines after they have breached the NTC. Provided you used the approved form in the first place, you can go straight to an NCAT application – you don’t need to go through mediation in that instance.
Also, you can seek penalties at NCAT for breaches of section 258 (below). This will require mediation first but could result in a maximium fine of $550.
258 TENANCY NOTICE TO BE GIVEN TO OWNERS CORPORATION OF LEASES OR SUBLEASES
(1) If a lot is leased, the lessor must give notice of the lease, in accordance with this section, to the owners corporation not later than 14 days after the commencement of the lease.
Maximum penalty: 5 penalty units.
(2) If a lot is subleased, the sub-lessor must give notice of the sublease, in accordance with this section, to the owners corporation not later than 14 days after the commencement of the sublease.
Maximum penalty: 5 penalty units.
(3) If a lease or sublease of a lot is assigned, the assignor must give notice of the assignment, in accordance with this section, to the owners corporation not later than 14 days after the execution of the assignment.
Maximum penalty: 5 penalty units.
(4) The notice must be in writing and specify:
(a) the name of the tenant and an address for service of the tenant, and
(b) the date of commencement or assignment of the lease or sublease, as the case requires, and
(c) the name of any agent acting for the owner in respect of the lease or sublease.
Note : An address for service of notices may be an Australian postal address or other electronic address, including an email address (see section 261).
(5) This section does not apply to the lease of a lot by the lessor of a strata leasehold scheme to a lessee who is the owner of a lot.