Lost water pressure e since rebuild of--

I recently had watercare come out and rebuild my water control assembly on top.They put a new piston in it, and several smaller parts,I now have to wait to long til the second flush the tank full again. IT DOES FILL .......just real slow. What do ou think went wrong, The rust is gone the brine tank pumps out as supposed too. I'm a plumber..just not a country plumber, What do you think??????????????please

I my self would have them come out and fix it on their dime....

They did the work and if it is not working as it should then they should make it right.