A landlord cannot lawfully end a tenancy simply to punish you for asserting your tenancy rights, such as reporting disrepair or contacting the RTB. However, a landlord may still be entitled to serve notice for a genuine lawful reason, provided the required conditions and notice periods are met. If you believe the notice is retaliatory, keep copies of your complaint and all messages, and consider referring the dispute to the RTB promptly. The RTB ultimately assesses the facts, while a solicitor can advise on your particular circumstances.