Stop dealing with the “front desk manager” and get the business card for the general manager and correspond with them via email.

I also don’t know why Marriott thinks the hotel has the choice. I dealt with this before in 2021 when Marriott announced the benefits guarantees were coming back. The Ambassador desk argued with me that it was the hotels choice, blah blah blah. Essentially would make the guarantee impossible to get since you don’t “get the points” until after you leave the property when they post and you can only make the claim on property.