Xfinity (Comcast) Gigabit, 1000 Mbps upload speed supposed to be up to 115mbps, actual is 23 mbps, down from 40 mbps

About 3 months ago I changed my gigabit plan to include mobile data and they were able to keep my gigabit plan as it was and lower my monthly cost.

My original speed was gigabit down, 40 mbps up.

With the "upgrade", my gigabit was to remain and as per the contract, the upload was supposed to go to 115mbps up.

Which has actually LOWERED to 23mbps.

I know this is not a modem capability issue as I have a comcast approved Arris S33 modem capable of up to 2.3 gbps speeds.

What gives?

Can anyone explain this?

Is there a number I can call?

I am an IT professional of 30 years and I KNOW this is throttled on their end, I need that throttle released and my speed increased to what I am paying for