I would check the battery - if you have one in an other car - try changing it over.
When I got my golf, alarm was doing the same thing - battery would only keep a very small charge - enough for one start - and then the alarm went mental.
Worth checking before you start messing with the alarm system. Try and find out what make it is. If you remove the trim around the steering wheel colum, they may be a reciever box with a make and/or model no and you may be able to find out how to reset, etc.