Forty Winks bed from Dial-a-bed. Worse buy ever

I bought a Forty Winks bed in August last year and it was THE WORSE BUY EVER. I spent a fortune on this bed that offered a 15 year warranty and within the FIRST 6 Months the mattress started sinking. After 8 months it was completely sunken. I contacted dial a bed in May and the service that I have received was ridiculous and laughable. This is supposed to be a reputable company! 3 months later and they still have not exchanged this mattress. They are extremely slow in providing feedback. I have to constantly contact them and I am getting no joy.