I run a Bane unit here in the states, with the economy being so bad, many people are doing the second cleaning for the year themselves. In 15 years of cleaning, I have never seen such soapy carpet. The consumer often uses too much soap, or the wrong product in those low power rentals and then soak the carpet.
I have tried other defoaming products, but I have to say Bane Clene's seems to work the best. I know its all pretty much the same stuff. An old timer, told me to add just a touch of a citris based cleaning solvent to the waste tank with the defoamer, I think it does seem to help.
Jon