What habitability actually covers
The essentials: effective waterproofing, working plumbing and hot water, functioning heating, safe electrical systems, sound floors and stairs, adequate rubbish receptacles, and freedom from vermin infestation.
It does not cover cosmetic issues, appliances not required by the standard, or conditions the tenant caused.
Notice is the precondition for everything
Almost every remedy requires that the landlord knew of the problem and had a reasonable opportunity to fix it. Verbal reports are easy to dispute later; a dated written request is not.
Keep copies. Photograph the condition. Note every visit that did or did not happen.
The remedies, and their risks
Repair and deduct — arranging the repair yourself and deducting the cost from rent — is available within limits on amount and frequency. Withholding rent entirely is a far riskier route: it can be a defence to an eviction, but if a court disagrees about the severity, you are in arrears.
Neither should be used without understanding the conditions attached. Getting this wrong turns a habitability complaint into an eviction case.
Do not simply stop paying rent
Withholding is a technical remedy with conditions, not a general protest. A tenant who withholds without meeting them is in arrears, and that is a strong position for a landlord. Get advice before, not after.
Report in writing and keep a copy
Date it. Describe the condition specifically.
Photograph and keep photographing
Progression over time matters as much as the original condition.
Allow reasonable access
Refusing entry undermines the whole complaint.
Consider a code enforcement inspection
An independent official record is powerful evidence.
Get advice before withholding or deducting
This is the step where tenants most often make their position worse.