How do you hire a serenade?

I'm not sure if that's what it's called. My boyfriend lives in Italy and I wanted to hire like a group of people that sing a romantic song either all of them sing in different tones or on sings while the others play or something like that. To go to his house or maybe wherever he is a restaurant or what not like they have in movies..Like in the lady and the tramp while they're at the restaurant(simple example).. I looked it up on Google and i cant find anything on it. I wanted to find out how to hire them,contact them..either one here or preferably in Italy..maybe a website or phone number or maybe a better name instead of serenade that will make my search better. Thanks!