Poor Quality Restonic Mattress

My mother purchased a Restonic bed in 2018. The mattress started to sag and the frame lopsided. The metal frame has become visible and springs are no longer aligned. With a result it has become extremely and terribly uncomfortable to sleep. The springs makes a terrible noise when getting on and off the bed. The retailer was notified and we were referred to the supplier. An inspection was done and the report we received was that due to the mattress having stains they are unable to exchange. I was referred to a senior who told me telephonically that he cannot accept a contaminated/dirty product back into his plant. We got cut off whilst in conversation and Coen made no attempt to contact me. I am unsatisfied with the service and feedback. I advised both Coen and Miles on email that I will be escalating. We are willing to have the mattress steam cleaned.The issue is not with the fabric but with the POOR quality of the mattress. I am not wanting a new bed/mattress but expect the manufacturer to fix or repair the springs, frame etc.I await your response.