Take it as a compliment, they obviously think you're successful and want a piece of the pie. If they were smart they'd concentrate on marketing their services instead of trying to steal others.
We had a funny one last week, turned up at an appointment and the lady thought I'd come to get paid, as she'd already had the work done. Turns out another local guy had phoned her and said I'd passed the work on to him and he could come the next day.
No idea how he knew as she had only phoned me.
Weird