In my opinion (good chance I'll get slaughtered for this, but...)
Dave is hardly displaying excellent customer service here (literally - its not bad, but not great), if it was me I'd have dealt with it via PM, but what damage is being done to Dave's business by posting this? Plus you're guaranteed a quick response if you deal publicly.
So why shouldn't he post his experience? Also, sourcing a second hand rad cap could be just as hard, if not harder than buying a brand new 'in stock' item. Especially if you've got cash to get an uprated item.
Mistakes happen, I know (we're only human). Its how they're resolved that matters.
Dave