Why is so hard to add a line?!

It has been two weeks of calls, and I still can't add a fourth line to my plan, so I have two bills between XFinity and ATT. The first agent told me they needed to run a credit report (fine, sure), but it would take up to 30 days? I escalated to a manager who said he knew what to do and would take care of it and call me back. Shockingly, I never received a callback. I'm now on the phone with "Emma" who just escalated me to "Will" who is telling me it will be 5-7 days?!? So far, I have wasted about 2-3 hours on the phone. Is this to be expected? ATT was so much easier to deal with.