You begin by submitting an application to the Residential Tenancies Board (RTB), explaining the dispute and providing relevant documents, such as the tenancy agreement, messages or photographs. Depending on the case and the parties’ agreement, it may proceed through free confidential mediation or a more formal adjudication, where an adjudicator considers written evidence and submissions. An adjudication decision can generally be appealed to a Tenancy Tribunal, subject to the applicable rules and time limits. The outcome depends on the individual facts, and any determination order may be enforced through the courts; check the RTB’s current guidance or seek legal advice if needed.