bad service from lewis

hi i am writing on behalf of my 76 yr old father he bought a black lounge suite (account number 004693/branch 262 )from Lewis Furniture. In the first month the lounge suite was already sagging like a flat Tyre .he phoned the and they came and took it, and brought it back in a good condition .2 months months down the line they were sagging again he called them again they came and took them back.The reason that they were able to come back was that the lounge suite had only one year guarantee. now its sagging again and anther repair has been booked the bad but was now the lounge was not even 1 years old but it looks like its 10 years old .he wanted to get an answer from them that when he bought this lounge suite for R7.600 he thought that he was buying quality, he wouldn't have never bought that lounge suite if he knew that it was going to break within 2 months after purchase. Now his stuck with a lounge suite which cost him R7.600 being pensioner having to pay R623,15 a month and it looks like it was bought 10 years ago, I feel that my father was cheated, when he bough this lounge suit he thought it was going to last at least five year not 2 months.