They don't have capacity to fulfill all their orderes, so they are going all out to supply the big customer. The little guy gets left till last. Sometimes there is no capacity for little guy's orders at all.
I've worked for a company like that. We made and fitted windows for buliding firms and local councils. We made hundreds of windows a week for these guys and had our own teams of fitters who we would have to keep busy. We also had trade customers who bought a handful of windows every week. The trade customers' windows often got left till last. They would be ringing up every day, and I would have to tell them 'tomorrow'.
"I can tell her you're all tied up in the projection room." Sunset Boulevard.