2004 Hyundai Lantra Body Control Module?

Electrical problem
2004 Hyundai Lantra Two Wheel Drive Manual

Hi, last night my left indicator light would not turn off, it was not blinking just stuck on at the front and rear of the car and also the little green light was on on the dashboard, when I turned the ignition off the light stayed on. My battery is now dead in my car. I called the dealership from which I bought it, the have told me the Body control module is gone and will cost 800 euro (Im in dublin Ireland) to get fixed. Do I have another option or do you think this is definitley the problem, I have only spoken to the dealership on the phone, no one has actually checked over the car yet. Do you think if the battery was disconnected this could possibly rectify the problem? Thank you for your help, kind regards Joanne