Complain

I bought a bed a year ago at sleepmasters and had a complain and it was solved and had the same complain with the same bed now I want an upgrade and already paid for it but now they taking me from pillar to post. How can I resolve this matter. I'm really not happy with this service. I did another lay by of other bed but now I am left with no choice but to cancel it because of the service it been a month now waiting for my bed