First, I would get on the vendor of this product very hard. Have your manager or even higher escalate it to somebody at the vendor with enough authority to ensure the resources to solve the problem. They may be able to help. If not, at least you've illuminated where the problem lies, namely with the vendor. This is not a time to suffer in silence. One question for them is whether your users should still be using this application while experiencing these problems.
Here is a pretty good article (at least at first glance) that discusses data corruption. http://www.quest-pipelines.com/newsletter-v4/0103_C.htm
One thing you might consider is writing a program that will move the data from this table to another table. Give it the capability to continue when it encounters an error (when it hits a bad block), and log the errors. This way you can save what you can. Maybe the vendor will provide a way to recover more data.
Good luck, Dennis Williams