I haven't had to use Zero Halliburton's customer service but I am decidedly unimpressed with Rimowa. Contacted them for some broken zipper pulls for the wifey's Salsa Air a few weeks ago and asked about some replacement dividers for my Topas 29" and received no response.
Called to see if that would make a difference. Spoke to a very nice rep (after being hung up on the first call - it sounded like I had interrupted a party )

She asked for photos in a follow up email and now they've completely ghosted me. As someone that has purchased a Topas Business Multiwheel, a 29" Topas Multiwheel case, a Topas Multiwheel IATA Cabin and a Salsa IATA I'm certainly not their biggest customer but I've spent a few $$$ with them.

Clearly not enough to even merit a response. I'm done with them.

UPDATE: It took a while but Rimowa has made it right in a big way. Please ignore that earlier ranting. I'd delete it but it's been quoted.