Your post is confusing and way too long, but is missing a critical detail. What airline operated the overbooked flight which apparently resulted in all of the ensuing problems? Was it BA or IB?

If IB, your complaint must be filed with IB.

Either way, if your complaint is as long as the post above, it may never get attention. Claims under EC 261/2004 should be 2-3 short declarative sentences because the right to compensation or a refund is typically based on a very specific set of facts.