well not so much a nightmare, but their customer service thus far has been horrific.
I bought a bed from them and had to pick it up from the warehouse myself. The bed in the showroom gives you a code for the frame and then another code for the mattress that fits that bed. I picked them all up (they come in several boxes)and when I get it home and pull it all out it turns out the headboard and footboard are the wrong sizes....I didn't realise until I put it all together.....they said last week they would phone me within 24 hours and I should have a replacement within a few days and 1 week later they haven't even phoned me back.
Now I've been waiting in the call queue since position 17 and I'm listening to fucking JLS.
Fuck you IKEA!