I think there's a problem linking my hazard lights to the alarm system ?

My renault megane cabriolet 02 plate. I think there's a fault between my hazard lights & the alarm system, which in turn is draining my battery. The hazard lights come on randomly, but alarm makes no sound. When you unlock the car THEN the alarm sounds, after this my battery is flat. Can anyone advise on this please, before I buy a new battery. Thanks