By the time DD3 was 6months old, she was sleeping for less than 10 minutes at a time. She'd drop off, relax, dummy fell out, big screams!
I was exhausted and had taken to sleeping with her cot along side my bed, with my hand over her face to hold the dummy in.
Obviously not a very safe solution, but sleep exhaustion drives you to despair!
I'd absolutely had enough. On the same night I moved DD into her own room and chucked the dummy in the bin.
Yeah she cried, but only for half an hour max. Then she went to sleep............til morning!!!
It was a harsh way of doing things, but it worked and we both slept like babies!