Restonic Bali bed is poor quality and also poor service from Restonic Bed

I have bought Restonic Bali bed in 2018 which gave me problem within 3 months and it was changed in March 2019. The same bed is sinking and I have logged a complain in January 2020, I was told that the representative will come and check the bed which never happen. We are in August 2020 and I am stuck with a sinking bed which was suppose to last me for 5 years, I have been to the store several times without getting any solution. What must I do next because no one want to help or giving me back my refund