Pricing dispute

I called Comcast after my bill went from $235.31 to $269.90. I asked if I could keep the same package and get a reduced price. The agent said no problem and reduced my price to $239.88. I was pleased until I went to use my TV and for that some of the premium channels were missing. I called back at least five times and have spent hours on the phone only to be told that my grandfathered in code is no longer available and can't be restored and my new price would be $273.00 for the same services I was paying $269.90. I was told I would get a $150.00 one time credit for the difference and now Comcast claims this is not in any agents notes. I have all the dated, times and agents I have spoken with. They agents are always nice and professional telling me there is nothing they can do. I'm a 22 year customer and diamond member and this means nothing to comcast. Comcast is forcing me to go elsewhere. I also have comcast internet at my place of business. This has been a very frustrating experience.