My husband and I are in the same situation. The person taking the check out inventory stated that the flat looked like it was in much better shape than it was when we moved in and has noted that on the check out statement. It has been well over 10 days, and over 10 business days even since we officially moved out. We were not contacted at all by our previous landlord nor our letting agency during that time. My husband contacted our previous letting agency to see when the deposit would be returned to us. Now the letting agency is stating that they are keeping part of the deposit, even though no damage was done, and everything was cleaned before we left.
My suspicion is that the previous letting agency doesn't want to give us the deposit back because my husband wouldn't pay an extra £150 to add me to a tenancy agreement a month before they tried to force him to renew. We never had trouble with our previous landlord, but we have had nothing BUT trouble from our previous letting agency, even when we were still with them. Managed property and it took them 4 months to fix a window... Not good.
Anyway, does anyone have any suggestions? The southern American in me is screaming to call them and pitch a fit until they relent, but I'd rather do this by the book to make sure we get our £700 something back in it's entirety!
Edited to add: I've spoken with our previous landlord now and he says he is more than happy with the way things were cleaned and how nice everything was left (better than it was when my husband moved in he said!). The letting agency have not contacted him AT ALL and therefore have either gotten their wires crossed or are trying to make extra money. I'm hoping for the former and that this gets worked out quickly.