How do i remove this stain from my carptet?

I have two dormer windows...at one time, the windows must have been left open and rained in on the carpet. Left a rusty colored ring. I tried to shampoo, use Spot Shot, seems like the stain shows all the more!!

Help. Do you know of any product or technique I can use to lift these stains???
Update: Would a company like Stanley Steamer know how to clean the rusty water rings out of the carpet? The stains are along the baseboard.
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