Security company change without informing clients

We were not even notified when our (then) current security company was sold to National. The once excellent service went terribly wrong as soon as it was sold! They have no idea who we are or where we are located. They called me for an opening signal at 9:30, after my shop already opened at 8:00. The lady spoke inaudibly and it took me a good few minutes to understand who she was, why National was phoning me, and what she was trying to say. They phoned me on Monday after I tripped the alarm, and the lady insisted to know where I was to verify that it was me... I then insisted to know where she thought I was (physical address of my shop) and she refused to tell me. How on earth would they find me if I had a real problem?