Mr. Sellers is a salesman who sells the TI-D 7000, a cleaning robot.
He once sold a TI-D 7000 to Jon Arbuckle, but does not tell Jon how exactly it operates- when it cleans up after pets, it disposes of the pets themselves.
Garfield and Odie are horrified with how the TI-D 7000 interferes with their normal lives. Garfield eventually finds the manual and uses it to reprogram the robot to clean up after pet owners. This causes it to go after Jon, who eventually realizes the problem.
When Mr. Sellers returns to ask if Jon is satisfied with his purchase, mud is dropped on him. The TI-D 7000, reprogrammed to clean "sleazy salespeople", chases down Mr Sellers; neither are seen again. Jon, realizing he never got his money back, runs after Mr. Sellers.