Dual Flush loo keeps pulling water in from mains every 10 mins?

We had our sottini dual flush loo fixed a couple of weeks ago. Water was running all the time inside. teh plumber fitted a new unit (like the old ballcock thing) But ever since it keeps pulling water in from the mains every 15 mins or so with some gusto. We have very high water pressure and this goes on day and night and you can hear it all over the house. It is driving us mad. Help