Sewing Machines Etcetera

My bobbin case had been damaged, catching threads, so they promptly replaced it and cleaned my machine at the same time.
But then, after less than an hour of use, the reverse (which had never been an issue) stopped working.
Since this hadn’t been part of the initial repair, it wasn’t covered under their service guarantee. Understandable, albeit frustrating, so I paid for the repairs. After getting my machine back, the reverse stopped working as I tested it.
This time, it was within the service guarantee period so the staff took it back to figure out the issue. I was told the mechanisms were beyond their capabilities to repair. Oh great.
So I lugged my sad machine to another repair shop and they found lubricant applied to the mechanisms had dried into a «hard resin». This alternative shop was able to fix the problem in no time, and my machine has been purring along happily since then.
This shop seems to have great classes and staff knowledgeable about the machines they sell, but I’m pretty damn peeved about the issue they created.
TLDR; They replaced a simple part, made new issue while cleaning machine, claimed issue was beyond repair. Other repairshop found the «lubricant» they had applied had dried into a resin like mess.