Phone number changed randomly

I’m having difficulty resolving this issue. On June 25th, I noticed that our landline number was different when it was correct the day prior. Multiple phone calls to support have not yielded results. Twice support personnel have said they’d call us back in a specified time and did not do so. The last individual tried to tell us we had always had that number! He did not believe us until he saw a previous bill with the original phone number on it.  No has been able to tell us why it was changed. We did recently change our plan but that was back in January. I saw a similar thread that was resolved by a Comcast employee poster but I cannot figure how to private message individual users. I would like my phone number back!