2005 Chevrolet C6500 injector replacement

Our truck started getting diesel in the antifreeze but was still running. It has a Cat engine so we called CAT and they told us it would be a month before they could get to it but that we needed new injector cups. We called another company that was referred to us by a friend. When they arrived at the truck they “started” it up but then instead of replacing the cups they replaced all the injectors and charged us an additional $579.54 plus tax for the CD’s that come with the injectors. Surprise, surprise the truck still ran but still had diesel in the antifreeze. They then replaced the injector cups and the truck is running with no diesel in the antifreeze. We questioned them about the work but they wouldn’t let us have the truck back until the bill was paid in full, so we paid. The bill was over $8400.00. How much did we get ripped off?