I work from home doing customer service on the phone. 
We get our calls marked for quality a few times a week and twice it’s been fed back to me that I have laughed at a customer on a call. 
I developed at nervous laugh when I became agoraphobic 10 years ago. It’s not a full on laugh - it’s just something I do when I feel awkward I guess. 
The customers have never complained and even if they did then I would explain that I can’t help it. 
How can I explain this to my work so they don’t keep giving it as feedback, it’s completely involuntary so I don’t know how I’d be able to stop doing it? 
It’s making me really self conscious and making me more anxious while taking calls.