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

We have a dual flush sottini toilet which has had a new "valve" (?) put in it. basically it was running water all the time and a plumber replaceed the entire inside bit. Sorry to be so vague. Now we don't have water running inside the cistern but every 10/15 mins it pulls water into the cistern from mains. We have very high water presseure and can hear this night and day all over the house. it is driving us mad.