Yes, Apple would have probably replaced it with a new one on the first visit. It sounds like the "repair shop" is milking you.
(Microsoft were doing this early in Windows 7 licence-for-this-hardware, change videocard, have to call Seattle)
or, they're incompetent. Nice, but incompetent.
The delays, however, are because Apple forbids third party to stock pile parts, they have to order as needed. So that's the aspect you should attack, if you really want to hate the fruit company.
Regardless of how I try to look at this, the problem is ultimately Apple. They’re facilitating a repair system which can take potentially months to repair a computer monitor. That doesn’t seem okay to me.
Shops adhering to the Independent Repair Program can't stock parts, but Apple Authorized Service Providers can.