Can Anyone Recommend Somewhere to Sort Alarm/Locking Issues

[Dave..]

Finally had it with my car, the alarm has never worked in the past 2 years, and now when I lock the car, it bleeps continuously, like there's a door left open.

I've had to leave it outside unlocked at the moment.

But can anyone recommend some where/some one who can fit new alarms, and which alarm to go for?

Thanks