Your landlord has a duty to make sure that your home is livable, that the conditions of the home are not a threat to the safety and health of the tenants and that the home complies with the housing code.
Call the local building inspector, and ask for an inspection. Also ask for a copy of the inspection report for your records.
The building inspector will tell the landlord to make the necessary repairs to fix the problem. If the landlord continues to refuse to make the repairs, let the building inspector know that the landlord will not make the repairs. The building inspector will demand that the landlord make the necessary repairs.
Despite the lease not being renewed in writing, the landlord is still likely to have a duty to repair this problem. There is likely a local ordinance dealing with it. If not, there is a general duty to keep the premises habitable. Yes, call the building inspector, as suggested. But also consider asking an attorney to write a demand letter to the landlord. Probably won't cost too much, and may get some action out of the owner.