tax credit change circ advice

Made changes to tax credit claim 4th Jan reducing childcare fees from 120 to 50 a week.
Not heard anything back yet no award notice nothing was told not to ring till after 9th Feb if not heard but i am worried about overpayments etc.

Is this because of a 4 week run on with fees because on the website it says should have award notice within 30 days but not heard.

Thanks in advance.