London Marriott Hotel Canary Wharf, Tobago Room

I would avoid this property at all costs. I just stayed here about a week ago and quickly noticed an additional charge which I did not make on my credit card. When I reached out to the property for clarification they had no note of this additional charge and sent my original receipt (despite my ask for them to verify the additional charge) and stated that was the only charge. 2 days later the charge fully clears and it is time for me to pay the credit card company. Again, I follow up with the property to reiterate this additional charge and request an explanation. This time they own up to the additional charge and admit it was a mistake and that it will be refunded swiftly. It is now one week later and there has been no refund at all and no further communication, so I was forced, once more, to follow up with the property for a status update and refund. As someone who has been Titanium Elite or Ambassador every year for the last 5 years this is hands down my worst experience with a Marriot property. The fact that I, the customer, had to identify and escalate a false charge is problematic, but I understand, mistakes happen. The fact that the property denied the extra charge and it took a second follow up from me for them to "identify the mistake" is what is extremely concerning ... really makes me worry about how many others this is happening to and what is the outcome if the customer doesn't identify the property's mistake. As a Marriott loyalist my expectation is that once I leave the hotel, that is the end of out, our mutual business is complete. The amount of time and effort I have had to invest into rectifying this properties mistake is very disappointing. EDIT (Response to Owner): I reached out directly on 3 separate occasions to resolve this. It was only after 3 attempts over the course of 1 week of direct communication with property that this review was given.