Where to buy good mattress in Addis

Hello,
I can't find good mattresses in Bahir Dar. There is either the strong sponge, or the big mattress with spring inside. Both have neiter a good confort nor a "long" life.
No slatted bed also.
Can someone help me: where can I find such equipement in Addis?
I've just seen nice bed in wood, but for the bedding, I don't know.
Thanks!