Ask them what the read out of the "road force balancing" was ? If the tires didn't balance below 20 lbs., or better yet into single figures, chances are that you may a tire (s) that is out of spec (out of round). This is not uncommon with low profile, high performance tires. It's what's commonly referred to as radical force variation . I went through this with a couple of new rear tires, wherein they wouldn't balance below the mid to upper 30's . And, ultimately they had to be replaced by the manufacturer .
Hunter GSP9700 Wheel vibration Control System solves wheel vibration and tire pull problems that balancers and aligners can't fix