Typically an agent of the company can act within their realm of authority.

A human CSA can give you a discount, and that is usually binding. They can't declare X corp is going to mail a box of donuts to you every day for the rest of your life and have it be.

So my expectation would be (in the absence of real world cases currently) that if you negotiate the AI into giving you a 10% discount on your bill.. it would be binding typically.

Now if there's prompt hacking involved or obvious attempts to trick the AI, that would not be binding.