30 Mbps after upgrade

On 7-29-20, I called to request an upgrade to  a faster Internet speed and was able to get the 1 GB package.  Before this upgrade, Speedtest was showing a download speed of approx. 120 Mbps, I had a Arris XB3 modem.  The tech stated that after 45 minutes of waiting on the line and him conferring with his manager, that i was all set and just had to reboot my modem.  I did and it was still the same at 120 Mbps.  I called back on the 30th and two techs on the same call told me my XB3 was not designed for 1 GB and had to get a modem that was.  So on 8-1-20, I went down to the Taylor, Mi XFinity store and received a replacement modem... or so i thought.  I got it home, followed instructions and suddenly was only receiving 30 Mbps on Speedtest.  After 2 hours waiting on the phone, the tech tells me that they gave me the wrong modem.  Wonderful.  On 8-2-20, i ended having to drive 45 minutes north to the Troy, MI branch, because Taylor wasn't open and recieved an XB6 modem.  I get home plug it, follow the instructions and STILL only 30 Mbps.  I called and after 2 hours on the phone AGAIN, was told that the package was not put through.  She put it through and still no good.   I asked her to re-provision the modem and she stated she did.  I'm not sure i believe her.   I talked to two techs again on 8-2-20.  They're supped to senmd out a tech tomorrow to my house to check everything on the outside, but honestly I don't think that's it.  I think it's something that entered wrong on their end and they're so stuck on following script that they're not stepping back to look at it.  This is by FAR the worst customer experience I've ever had with ANY company.  Any recommendations would be appreciated.  Five days with no resolution is unacceptable.