Upload Speeds are dismal

I have been on the 500 MBPS plan in Florida for several years now and I just realized my upload speeds are terrible. Over the course of a week all speed test I run come back between 5 and 10 Mbps. I messaged the chat agent who told me that's the current speed and if I wanted more I would have to pay almost $100 more a.month. I asked him to troubleshoot he said no, I asked for an upgrade to ensure I get at least 40 Mbps he said he can't I asked for the xb10 modem to try that he said no. I'm so frustrated with Xfinity they advertise symmetrical speeds for some people and 40 mbps for me but I'm getting neither.