I do agree here. Questions for the online poster:

1) Do you know whether the rate was an extended stay rate? Sadly, Marriott is terrible with this on their emails. Call Marriott and ask them to check up on the original rate and if it was a long term stay rate or regular rate.

2) I know others may disagree here, but the fact that a hotel employee, a representative of the company, told you it was ok for you to check out a day early, you have every right to believe them. Management should properly train their employees. It is not a customer's burden to determine whether an employee is following company policy or not. If the employee. If you were told it would be a problem, I'm sure you would have stayed the 5th night or just sneak out a day early.

3) Like others have said, always get a physical receipt when checking out of a hotel. Yes, it might mean extra time. But it is much easier to dispute a bill in person than over the phone. When over the phone, you are easier to ignore.

Sadly, with these types of disputes, they are very difficult to handle. Businesses ultimately want you to just to away so that they can keep your money. If you are willing to fight, there are some guides you can follow:
https://www.elliott.org/answers/how-...sumer-problem/
https://www.elliott.org/ultimate-con...the-right-way/
https://www.elliott.org/company-cont...ntact-details/
https://www.elliott.org/blog/5-magic...sumer-problem/

Best of luck!