Did the change request come complete with specific requirements
I get that you do need specs but c'mon, if you ask a plumber to fit a pipe from A to B and he uses one made out of cardboard would you think it was reasonable for him to say "well you didn't specify it had to carry water, pay me 3x as much to put it right". And then you find out that this is the first time he's even seen a pipe, but his business card says "senior plumbing expert".
You expect a basic level of competence and familiarity with the problem domain and good faith from any professional whose services you hire.
Also consider that a program is a spec, and if you are going to explicitly specify every little detail then you might as well just write the program yourself, there is literally no sane reason to put an outsourcer in the middle.
Unfortunately, that's not how the game works with the large services firms. The salespeople and account/project managers run the show. Their business isn't selling expertise / solutions, it's selling the maximum amount of billable hours at the highest possible margin via the illusion of expertise / solutions. (I say illusion because if you read the fine print of one of their typical contracts, there's very little actually promised other than providing warm body of type X for hourly rate of Y)
Exactly, this is everything that I hate about requirements management and requirements-driven-development in a nutshell. Way too often it just means: "we're actually too lazy / overworked / uninterested / have targets that don't align with the long-term best outcome, so we'll just force you to write down requirements which we know can't and won't ever be complete." It's the best way to cause internal politics to fire up and projects to belly up.
I get that you do need specs but c'mon, if you ask a plumber to fit a pipe from A to B and he uses one made out of cardboard would you think it was reasonable for him to say "well you didn't specify it had to carry water, pay me 3x as much to put it right". And then you find out that this is the first time he's even seen a pipe, but his business card says "senior plumbing expert".
You expect a basic level of competence and familiarity with the problem domain and good faith from any professional whose services you hire.
Also consider that a program is a spec, and if you are going to explicitly specify every little detail then you might as well just write the program yourself, there is literally no sane reason to put an outsourcer in the middle.