Look up the address on www.phila.gov. You can find the name of the owner in the property tax record section. Just click on "Pay Real Estate Taxes" and enter the address. Then call L&I and tell them the details and owner's name. Forget calling 311. Call L&I directly. Get the name and direct number of the person you talk to. Make sure they know YOUR name. Ask them what they intend to do about it. Call periodically to follow up. You have a better chance of getting results if you do this. But, no promises of course. After all, it's the city. Good luck!