You may not want to hear this, but
Years ago (we're talking the 1960's) I attended tech school in Indianapolis. I landed a job working for a small TV and radio repair shop, downtown. Guy had been there for years. I got the easy repairs, replace a tube, install a new capacitors, etc. After I got it running perfectly, he'd then come over and replace one of the tubes, usually a horiz output, with a used one.
I got curious about this and he told that he tested the replacement and it was around 75%; good for about 6 months. Then the owner would call about his TV going out and we would get more business.
And he was right, about 6 months later they called. Picture was rolling. Learned a lot from that old schister.
Point is, all your mechanic needed to do is put an impact wrench on the bolt and spin it off. Then put on the new blade. An hour at best (with a free acting class on how much trouble it caused him). Nothing else should be wrong, that wasn't before.
Choose a different dealer in the future. This guy is sitting you up for more $$. (And it won't be over once this is fixed. Once that old man in Indy got a client, he never let go).