Oooo! Someone else being punished for extending their family!
My daughter is 8 months old tomorrow and still doesn't sleep through the night, we are getting there though as she now sleeps from 18:00 till 01:00 and has a bottle before sleeping again till 05:00 at which point she is awake. Some tips on how to improve things:
First off, if they aren't sleeping in their own room yet, move them. Your tossing and turning at night will bother them.
If the twins aren't on solids yet, slap yourself and then go ask your pediatrician how to start this. Amazingly they all have their own view, our ped laughed at us when we asked about baby cereals and started us off on yellow vegetables, then added fruit, then added oats and mealie meal and tonight we start on meat. The solids take longer to digest and keeps the babies fuller for longer.
Try not to give them too much attention at night if their dummies fall out and do not turn on lights in the room! If you have an angelcare the little blue light should be enough to feel around and find the dummy, pop it back in and walk away. This is difficult but eventually it works. (I am not advocating that you should let them cry it out though)
Check your bed time routine, babies actually like having a bath, then a bottle in a dimly lit room, then a dummy and some rocking. Do not provide stimulation at this point.
Check the temperature in the room, ifs its too cold or too hot they will be uncomfortable.
And finally a highly controversial suggestion. Find them a creche...they can actually teach your babies to fall back to sleep on their own and sleep through most noise. Finding the right creche is a curse though, you want something with a low caregiver to baby ratio, nothing more than 3 babies to 1 caregiver or 5 to 1 at a push with a resident occupational therapist to watch the babies development. I know most people will advise against putting your baby into a creche at such an early age but for us it has only improved things. Baby loves the social interaction, the school managed to teach her to sleep through anything and in general she just seems happier to not be stuck with us all day.