RTI shared with Universal Credit Department

We have submitted three files for November pay to HMRC, all three files were acknowledged.
First file contained overpayment errors impacting 1000 members of staff.
Second file reversed the information for the 1000 staff.
Third file contained the correct pay (tax, NI, Pension etc) information for the 1000 staff.
Only the First file has been shared with the Universal Credit Department meaning that employees have had universal credits stopped based on an overpayment file.
The general help line can not help me, I am now waiting on the Employer helpline.
Any other advice on what we can do to get this corrected? any time of year is bad but December makes this doubly worse

Hi JSK 
You have taken the correct action and the options available at Employers: general enquiries should help. I note that you are currently awaiting your call being dealt with.
Your employees must, individually, contact the Universal Credit: Contact Universal Credit who will assist them
Thank you.