horn went off but there's no alarm on my car

[TI3VOM]

Last night my alarm went off again for the second night in a row this time at 12:18 now I went to holden and told them what had happend the guy told me that since it was a continuios horn sound not beep beep beep that it doesent sound like the alarm he didnt know what it could be he pointed me in the direction of an auto electrician up the road to save myself some money.
I checked my relays and I do not have a theft horn one for my car or the metal terminals in the relay socket where it should go so it's definantly not an alarm what could be the cause of this? Oh and my keyless entry does not work when this happens so i have to get into the car manually appreciate any feedback

I know this is the second thread about this issue but in the last thread I was under the assumption that i had an alarm in my car

[strgas]

Horn contacts and horn pads have been known to distort with heat and do strange things in the heat and when they have cooled down again .

[TI3VOM]

Awesome thats has to be it that is exactly what I thought it is only because it just hit the 30degree celsius mark in canberra and I work in retail so the car gets parked up on the roof for 9 hours a day so the first night after sitting there in the heat it cooled down to a certain degree the contacts touched and off it went.