Promise a locked in rate for 3 years

Not sure if anything can be done. On 5/30/26 talked with a Shivam about my rates. In order to get me to stay as a loyal customer was told to sign up for 500mbps at $55 with a $10 credit on my next billing cycle for 1 month. After that 1 month I will be getting a locked in rates at $30 for 3 years for 300mbps. Saw my plan updated but no credit or any promotion at locking in my rates. Tried to follow up with 6/19 and apparently there was no record about that promotion and in order for me to get the $10 credit I need to pay by checking account not credited card (which I was not told). I save the transcript as well as screenshots of our discussion. Not sure if I was just being lied to?