Trainz parts service has been excellent lately. I had some issues (wrong items, missing) several years back. Tried buying again and in the last couple of years, service has improved greatly. Personal responses from service people is exceptional...quick to credit on damaged items (happens rarely). More importantly I get credit for excess shipping costs.
That's one needed improvement-to set up shipping charges that increment minimally for the small parts being ordered. E.G. $5 for first item, $0.50 for each subsequent part, subject to weight obviously. I'd rather pay close to the true charges than wait and receive credit for an overcharge (which they do reliably,, however)