Cloud nine Ultimate mattress collapsed

Bought a Cloud nine Blue Ultimate PT king size bed in December 2022 after 8 months the mattress is collapsing, spoke to the shop where we bought it and they were very helpful and logged the complaint with Cloud nine / Rest assured who took 3 weeks to eventually come out to see the bed after a few emails. The Cloud nine representative did inspection and left, received an email following day to say there was a mark on the mattress so they could not replace or honour the 25 year warranty. This is the worst after sales service I have ever experienced, would not recommend Cloud nine or Rest assured beds to anyone