Horn not working

Hi all, my horns not worked for as long as I’ve owned the car. I’ve recently change the squib/clockspring that didn’t work. I’m not getting any power to the horn it’s self but the horn is working when you you a test on diag tool. I can’t hear the relay noise when I press the air bag but if it works on the diag tool test then power must go through the relay for it to work? Really stuck and need to sort it for MOT