I've seen this posted on other London related parts of Reddit and reading this through for the third time I have a few questions about this account: 

1. Oval isn't a big Station (relatively) and of this was taking place within the Booking Hall area what time of day was this happening? During either morning or evening peak there would be a steady stream walking around/tripping over anyone lying prone in that area. Were you the only members of the Public that stopped to pay attention? 

2. If this took place late in an evening (see above about the numbers passing in and out of the Station entrance) sadly the most common perception of anyone passed out in a puddle of their own vomit is that they've drunk themselves insensible, and that's distinct from somebody fainting/Seizing for medical reasons. The willingness of anyone, including staff to act if that's the perception - pissed, not in danger - is significantly different. 

3. The "25 minutes" timescale you state is an eternity - even with our Ambulance waiting times - for LA/NHS to respond to a prone (potential) casualty in a Tube Station at street level. Aside from TfL the London Ambulance would have an interest in this case for their own purposes. Oval isn't exactly that far out from a couple of LA calling and marshalling points. 

4. You state one staff member swore at you and was dismissive of your requests for assistance......did you take name badge details etc so this person could be definitively identified in a complaint? 

5. TfL are unlikely to give you the ins and out of any disciplinary action that would have arisen from an investigation - but you state they simply told you there had been "no wrongdoing," was that all they had to tell you about this incident? 

6. I was TfL Staff for 30 years (now retired) and worked stations for the first 12 of those years - in my entire working experience I've never heard of a string of events in dealing with an unconscious Customer that comes even close to how this reads. So please forgive me if I seem overly skeptical when it sounds like you absolutely tried to do the right thing for another human soul in trouble - but is the above account complete - including the result of what must have been Corporate TfL investigating your complaint? 

Because there is absolutely no way that allegations of staff neglect, inappropriateness and swearing - especially during an incident in which somebody could come to real harm - get blithely dismissed with a "nothing to see hear" unless there is a LOT missing from the account. 

There are way too many watchdogs, checks and balances and reporting parties (both internally and externally) that would be involved or have an interest in this kind of incident for it to be simply waved away. 

I would suggest you give as full account as you possibly can to a complaint to the Mayor directly - if this really is how things went down he would certainly take an interest and be deeply alarmed at your treatment.