I've been scammed

I recently traded in my s24 plus towards an s25 plus during a promotion. Up to 1100.00 towards the new phone. After speaking to a customer service representative they assured me that I would get the full 1100.00 trade in and a device credit of 45.00 per month for 24 months. I told them that unless I got the full trade in amount I would not trade in my s24 plus. Again I was assured that I would be receiving the full amount. I just looked at my bill and they are only giving me a 23.00 per month credit and fair market value of 295 for my s24 plus!!! I chatted with a representative and they said they could do nothing!!! I have screen shots of the promise by the other representative. I feel scammed. I would never have traded in my device for 295!!!!! Xfinity has really gone down hill.