What to do about my Landlord?

We pay $650 a month for rent and our shower has a constant hot water leak so we have to shut the water off to the entire house when we're not using it,plus the drain to the shower leaks into the basement Our chimney leaks in the basement when it rains and we may have a possible oil leak from our heater. We have contacted our landlord 2 WEEKS AGO!!!! and he has still not gotten anything fixed? WHAT CAN WE DO?????