Cell c settlement letter with invalid ID number

I have struggled really with cell c for months finally they gave me the settlement letter but with an invalid ID number hence the settlement letter is considered void because not even the credit bureau will take that I have tried communicating with them via email and telephonically of which the turn over time is 24-48 hours which is now over a week from the date they sent me the letter and the time I responded via email now telephonically the 24-48 hours does not seem to work meanwhile other organizations have declined their settle letter when I sent it to them due to the invalid ID number