We have the ikea vimle sofa bed. It is so uncomfy to sleep on. Are there any tips to make the issue better. The issue is, that even though the soda bed pull out frame looks level, it is not level once you have the mattress on and try to lie on it... it dips in at the head bit where the pillows go. There does not seem to be mattress upgrade options either and this thing was over 1k ...