When did I become Cassandra?

I warned them.
I warned them that we'd modified the FAX-modem code.
I warned them that we probably didn't want to upgrade it unless something was actually broken.
I warned them that, if they upgraded to the new Hylafax code, they'd need to figure out exactly what we'd changed in the old code and make sure we either made the same changes to the new code or didn't need to make them.
I warned them this wouldn't be trivial, and it wasn't something to be handed to someone who wasn't willing or able to get intimate with the internals of our app and Hylafax.

They assigned the work to the outsourced devs in India anyway.
And those devs ignored my warnings.

You can probably guess what's broken. And while you can probably guess how badly, your guess is probably far short of the reality.
And I'm not even going to estimate how long it'll take to fix things. It's Not My Problem. I have a full plate of my own, let the India dev clean up his own mess. And if it screws up the schedule, well, that's Not My Problem either.