As it stands you don't have much proof, but it would most likely be very easy to acquire absolute proof. Under the Criminal Code Of Canada, it is legal to secretly record private conversations, so long as you are a participating party in the private conversation.
From C-46 Sub-Section 183.1
Where a private communication is originated by more than one person or
is intended by the originator thereof to be received by more than one
person, a consent to the interception thereof by any one of those
persons is sufficient consent for the purposes of any provision of
Reading the code at length and other resources on the topic, pay special attention that you cannot be secretly recording conversations you're not a part of. Sticking a tape recorder somewhere and walking away is definitely going to be classified as criminal.
Simply phoning up the landlord and starting a conversation or argument about the issue will most likely lead to the landlord confirming the facts, one way or another. Put speaker phone on, download an app for recording and start doing so. Or if in person, turn it on drop it in your pocket. Discuss the issue until you get remarks confirming your facts. I've been in this situation, and as tempting as it is to rub it in their face that you've got them on the record, keep your mouth shut.
Proceed with whatever legal recourse you will. Pull out this evidence as an absolute last resort. You can savor that feeling of busting someone in a lie one-hundred fold when you have them tell the lie to the court, then play it back for everyone to hear.
Most Canadians I've spoken with can't believe this is legal. Talk to a lawyer, call up the non-emergency line of your local police, they will confirm it. I've done this without issue personally and have helped people do it successfully against even the police. Be a clear participant, you're in the clear.
More resources on the topic here and here.