Unfortunately this happen on daily basis on real life.
Not only in usage of libraries but on outsourcing work. The company selling you the solution have no idea of the technology they use. Thus when something goes wrong, they have no way of solving the problem.
But, for them is not a problem, since you already pay for it. Don't worry, once the problem is solved they will be charging again for an upgrade. And PHB will be the one taking the decision of buying their crap again.