Pls help me

Hy I bought a bed in Lewis furniture the mattress is not in good condition I complained about it they said the will get back to me I'm still waiting when I get to the shop they saying the manufacturer told them no one should return the bed his not taking any beds for return I bought the bed cash can you help me pls I really need help cause I slept in that for less than a year but it's not in a good condition when I reported the bed they say the bed is for small kids but when I bought it they didn't tell me that story