I must say I've had a similar experience with the TfL-run ticket office at Abbey Wood. Night and day difference from when Southeastern used to run it (I think the Southeastern staff got redeployed to other stations and TfL got their own people in).I bought a couple of Thames Branches Day Rangers at Ealing Broadway.
Admittedly they are valid there, but they were for the following day. The very friendly clerk gave an extremely good impression of TfL, clearly knew exactly what we were after and sold them as quickly as you'd expect a single to Paddington.