YES, you did pay good money to morons. I have heard that the abs module can be difficult to bleed but then you have morons working on it. Not your fault you just paid and expected it to be right. They have your money and now just want you to go away. I would find a better shop and pay to have it straightened out. You already know what the idiots want. Why pay $2,500 more plus possible labor to install the abs. Get out of there. They shouldn't be working on brakes. Cobbler rip off artist.
A buddy had a 2001 Chevy Avalanche that needed the brakes bleed and could never get it right. He finally had it done at a dealer because it needed a TECH2 handheld scan tool to pulse the abs module. It would run the motor and pulses the internal valves.