Child benefit compliance team - not answering phone line

Hi
my clients’ CB claim is suspended due to an info request from the CB compliance team. The clients have sent back info but no response yet and still not paid.
We were given the compliance team’s number of 03003229079 plus an extension number, but ringing this several times you can’t even get on hold; the recorded message always says that they are busy and can’t answer the call - call back another time.
The main CB line has put in a request for a callback three times with no callback forthcoming.
Will try tomorrow first thing 8.30am but it’s quite frustrating not to even go on hold, as we’re not sure if they now have all the information needed to resume the claim, and when payments will be resumed