I have to look at this from a business point of view. If I promise my customer to deliver such and such on a certain date, and then one of my vendors doesn't deliver, what do I tell my client? Certainly if I tell him that my vendor dropped the ball, he would quickly tell me that he doesn't know my vendor, nor did he hire him to do the job. I made the promise, not my vendor.
That being said, crap happens, but there is still the responsibility to make it right. How you go about that and how long it takes determines whether or not you continue to do business with the client, and very possibly with other prospective clients who will be told about the issue. Do a good job and no one will notice, but screw up and the world will know about it.
While my example may be different from this situation, the fix remains the same. You are only as good as your word. If you don't stand behind it, you quickly loose credibility which is evident from this thread. If you want to keep the client and gain future business, you do what it takes to deliver the goods and satisfy the client. Then you go after the vendor who let you down.
Best.
