That's pretty close to what happened to my niece. She took her 88 Honda Accord LX (Christine, as I call it) to a local mechanic to get it repaired. The car runs better. However, she paid to have a new radiator and overflow installed. The parts were not only not installed, but they were taken back by an employee and the money pocketed.
Or so that's the story. The shop put a copper fitting in, instead of replacing the parts as paid to do.
The same with several seals and gaskets, and all four engine mounts and the trans mount.
$400 worth of parts and labor that was not done.
And it gets even better - the guy puts my sister "on hold", but messed up. She overheard the mechanic basically complaining that my sister was a 'pain to deal with'.
Mechanics are just like General Contractors; ya gotta watch 'em like a hawk.