What should I do if my child was inappropriately touched at daycare by 2 of the other children and the provider did not tell us?

We found out from our 5 year old daughter that 2 boys at a temp daycare put their fingers in her vagina on 2 of the 3 days she was there. She said the Provider punished the boys by putting them in the corner but the provider told us nothing about the incident. We don't know what we should do. The daycare lady was someone we trusted and used for a couple years. When our daughter was old enough, she moved to a preschool. We usually use her every year around the holidays for a week or so. Now we have lost all trust and don't know what we should do about it.