IM ONLY GETTING 20Mbps WHEN I AM PAYING FOR THE 1200Mbps

​I am paying for the 1200mbps package and I am CONSTANTLY getting under 20 mbps. 1% OF MY DATA PLAN. ​

​This has been an ongoing issue since 11/2023 and xfinity has done nothing but replace the modem with an even worse one than before. How do I pay $100 for 1200 Mbps and only get 20Mbps,?? Thats absolutely revolting.  ​
​All the resets, unplugging the router, and necessary tests have been done. I am at a loss of what to do here and am about to switch my internet provider because xfinity has always had some kind of issue with the way they do things​

​Does anyone else have this problem and can suggest something to do?​