Quality Digest

From what I have read about 6sigma I get an impression that the theory is primarily focused on the company and its processes. What I miss is to see how the theory is applied for the end user and during the life of the product.
Mr. H.J. Harrington makes a case in the point in the following article http://www.qualitydigest.com/currentmag/html/harrington.html

Indeed, if we look at products that come from those 6sigma companies wery few of them are "6 sigma in use". Companies may have six sigma, but what counts is what the customers see and feel during the life of the product/service.
My relative has a printing company and some machines are from those 6 sigma companies. During my numerous visits those machines would fail several times during the day. Indeed they have the policy of comming on-site within 4 hours to fix it. But is this six sigma? I would not say. Good sewrvice? I would not say. My relative has to pay sky high monthly payments in order to get this kind of service. If they are 6 sigma and they are so certain in their product they would have provided it for free. What about six sigma in services? What about six sigma in customer relationship?, etc.
There are lot of questions that I can't find answers for in current six sigma theory.

Do you have any references to some work done on how to deliver 6 sigma to the users/customers throughout the life of the product/service?

I would like to hear other opinions as well.

Best regards