The problem you are describing is commonly refered to as "ignition-OFF draw" this is when something that is supposed to turn off with the ignition remains on with the ignition in the OFF position and causes the battery to drain. If you have a meter that can measur voltage and amperage and have a little experienc and know how to use it, I can guide you through the process of determining the actual cause of the problem. Yes, it COULD be a bad ignition switch. Yes, it COULD be a sticking relay. But then again, it could possibly be a relay control circuit shorting to ground, in which case replacing the relay and/or the ignition switch will not fix the problem. There is no way I can tell you for sure without FIRST doing some testing.