What's the brand and model number of the Digital Converter Box TWC uses at your client's home? Because some TWC divisions use Cisco & Arris equipment while other ares use Motorola equipment. I have an older Cisco DTA box and my regular TWC DVR Atlas remote controls it, as does my MX-890 (using the same code set as my former SA8300HD and current Cisco 2-tuner and Arris 6-tuner DVRs).

And recently TWC started deploying newer models that are RF only (no IR window) so you can hide them behind stuff, and they can't be controlled by the regular IR remotes that come with their DVRs and Cable Boxes. I recently ran into this when my mother-in-law had to get a DTA box for a bedroom TV and her big lighted TWC remote from the living room wouldn't control it. Turned out the box is RF only. I noticed her box had a 3.5mm jack on the rear labeled "IR" so i connected an old IR Receiver and the box now responds to her big lighted remote (the little one that comes with the DTA is crappy and her 91 year old eyes can't see it).