Name change

Me and my wife are going through the marriage process as I mentioned in other posts for her to get AOS. Another issue is we can’t get anything back from the IRS for her name change! We sent it in 3-4 weeks ago the letter with the marriage certificate to change her last name on her ITIN number but we’re not sure what to do next. Any advice on this? Has anyone els went through anything similar? It’s like we don’t even know if they got the letter!