Sounds like you might be getting radial pull, that happens sometimes if you get shity tires.
Wheel rotation is just him just switching tires from front to back. Wheel balancing is if you are feel any vibration at X MPH and the wheel is basically whoobling.
Are you lowered? I think you are getting radial pull. Have him mount / un-mount the tire you replace to the other side. If it pulls to that side then you are getting radial pull and have him put a new one on.