Flood in the inner circle of provider's Internet

The hardware in the inner circle in the provider's network worked incorrectly and therefore there was flood for an hour. They said that it wouldn't repeat again anymore, and that that flood was not in our user network. Is this 100% correct?

(As there was no Internet because of that flood we couldn't check the situation properly from our side.)

These terms are too ambiguous. How did you determine there was no internet? Generally a flood will result in erratic connectivity. You can do pings and traceroutes to attempt to determine the boundary between your network and the provider network. Was connectivity to the internet erratic or down.