You are not the only person to have suffered problems post recall, and it seems to have been quite a widely reported issues (albeit more with cars in the US than in the UK). And the problem is almost invariably bottom end bearing failure as a result of sealant debris blocking the oil pickup after the engine has been resealed improperly. If it's been only 200 miles since the recall, and you have the same failure, then I hope that they really wouldn't be able to point the finger at anything else - the failures are usually within a couple of thousand miles.
How were you driving when the knocking started? Did it start when driving normally, was the engine warm, etc? Is the engine otherwise generally well looked after?
I had my recall done a couple of weeks ago. Before booking, I had a chat with the service manager and luckily, he not only knew about the issues suffered from recalls, but said they had done between 10-20 so far with no problems. That put my mind at ease a bit, but I have to confess, I reset the trip computer the moment I picked it up, and have been keeping an ear out for knocking noises. I've done about 550 miles so far, I don't think I'll be able to rest easy until I have a couple of thousand under my belt.
If I were you, I'd maybe start finding out details of as many other owners who've suffered post-recall failures as you can. It will be easier to fight your case if you can demonstrate that this is a much wider issue.