Car wasn't heating. Had thermostat replaced and coolant refilled.

If your car is not low on coolant now, likely the heater core that provides heat is stopped up with rust. This is something I have seen many times with that year and model car. Many times we have been able to back flush the heater to get the coolant flowing throught it so you will have heat. This method of repair does not always work but we usally try that first trying to avoid the major exspence of replaceing heater core. My shop is in your area should want to call us so we can exchange more information.

First you have to get the leak fixed.