Have i ruined my power steering?!?!

Hey guys,

I've just had a problem with my power steering.. long story, but here it goes:

About 4 months ago i had the power steering pump changed because there was the whining noise, and apprantly the mechanic said that was the cause of fluid loss. Then about 5 weeks later, the same thing happened, but this time it was found to be a minor leak in the PS rack! So since then, its been lasting about 4 weeks then slowly into 1 week, and now into every 2 days to top the PS fluid up after it becomes empty. I just booked in the car for next week to get the PS rack fixed which all sounds good...

But then today, i drove it out with topped up fluid, and about 1/4 mile later, the PS just fails and i have to man handle the steering wheel to get the car off the road! So i topped the fluid up again to get home, but still no PS, and when i checked the fluid level when i arrived back home - all empty, plus a burning smell from the opposite side of the PS resevoir.

So just a few question... did i just reburn and ruin the PS pump? Was that the burning smell?
And how could the fluid all go empty only after 1/4 mile when it was ok yesterday? (PS rack has gone real big, or more likely the pump just had it?)

hope you guys are able to give me some pointers here.. i know i'm a douchbag for keeping the problem so long thanks!