Denying a phlebotomist

So I have my 3 hour GD test in a day or two during my one hour test I had my blood drawn by this guy he was good it didn't hurt that bad but then got my blood drawn by a different girl, I was waiting for him but she called me over well when she did it, it HURT SO BAD ! I have a highish pain tolorance but it hurt bad during and the whole day after also left a big bruise. My question is how do I go about refusing her if I get her this time and how would I do it non chalantly, there's usually 4 main people that draw blood.