(first of all this belongs in the BA forum, as it is really more of a rant than a trip report)
My sympathies to your wife for what sound like quite painful medical conditions. But, even with the standard hyperbole that is common among these types of posts, it doesn't seem that BA did anything particularly poor here. No airline is truly qualified to handle passengers with serious medical conditions. I think BA (and its partners and airport staff [who are not BA employees]) did about as good a job as can be reasonably be expected. If your wife's condition is so poor, I think you might need more medical assistance than a low-wage wheelchair pusher or 17 year old girl can provide.
Case in point:
5 - During check-in the agent provided two seats far from the bathroom (although in J, the seats are never more than a few rows away). You asked them to be seated closer to bathrooms (a perfectly reasonable request given the medical issues) and the agent did so. How should the agent have known what seats you wanted?
Again, my sympathies with your situation. But I am not sure you will necessarily find better service elsewhere. The bottom line is, flying 30 hours with a serious medical condition is almost surely a difficult journey.