Inferior Simmons Product and Service

We purchased a Simmons Superior King mattress in 2010. Unfortunately soon after purchase the mattress started to feel uncomfortable and started "dipping" where my husband slept. It has been uncomfortable from day one and is dipping now on both sides. We are now sleeping across the mattress and base to at least get some sleep.

We are extremely disappointed as the mattress was expensive. This mattress has a 12 year warranty and surely the mattress should not have been faulty from year one and should last at least the 12 years? Simmons want to charge to repair the mattress under the warranty but will only give a 6 month guarantee on this repair. They are absolutely NOT prepared to extend that to a 12 month guarantee on our request. What difference does 6 months make to Simmons?

Surely Simmons, in good faith, should be prepared to extend this by another 6 months given the experience and discomfort we have had over the last 7 years. We were in fact, (by even considering the repair option) giving Simmons another chance. If they have confidence in their product, it should surely not be a problem to extend this by an extra 6 months?

Is it because they know that the problem will reoccur? We are completely dissatisfied with the response from Simmons South Africa and want to advise others of this inferior product.