TMobile refuses to honor contract

24 year customer on a family plan. Friday was looking into my own essentials plan and talked with a Tmobile website chat agent about starting it. I told them whatever I do I want to keep my number that I've had for 24 years. They assured me I could and I made sure the number was released from the family plan. The sales agent talked me into the go5g plus plan in order to get a 800 off new phone (I don't need a new phone whatsoever but I thought it was a deal worth taking) multiple times I checked that I would be able to keep my number and I asked one more time before signing the contract and authorizing payment, they assured me I could keep my number. Today (Tuesday) my new phone arrived and I went to set it up with my new account and now they are telling me I can either have the 800$ off OR keep my number. I told them that I confirmed numerous times in the chat logs that I could keep my number and now they refuse to honor the deal their agent made. They talked me up to a more expensive plan and talked me into upgrading my phone and now I'm stuck with a new number or paying 800 more than originally agreed upon.

How can you expect your customers to honor your contracts when you can't even honor them T-Mobile