This place is NOT in a hotel type facility.
It is NOT located at - or even near Marble Arch.
Upon arriving at the address we found a door in the middle of a block with the street number above it. The door was locked. There were three - NON-FUNCTIONING door bells, NO sign or any other indication of how to get in.
When we returned to central London and got access to our email we found a message sent at 10am that morning telling us that we must call a number to get someone to come over and let us in. As we checked out of our previous hotel at 8 am that morning, we had NOT received the message.
We called and were told to travel out to another side of London (Kensington) to get the key.
We took it back to the 'Flat' and found it did not fit the front door. :-(
As it had already taken us over 3 hours to try to get in, we informed the hotel in Kensington that we were returning and expected to be given a room there.
When we arrived back at the hotel, after 4 hours of traveling around London we were given a room there. :-)
HOWEVER, it had taken half a day of our London stay and been a totally bad experience!
NOTE: There was NO indication on the Expedia site that this was a single unit with NO staff. We were NOT told that is was some sort of an air B+B arrangement. (we booked it on the Expedia Hotel website) and THERE was NO indication of these things - nor even a local phone number on the Expedia site.
WE ARE VERY DISAPPOINTED with Expedia for this situation.