Help with Twins at Bedtime

I'm a single Mum with 7 year old twin girls. They have very different characters and the biggest problem I'm having is getting them to bed and staying there. The bed time routine I've been using is they brush their teeth get undressed then sit on the bed with me while I read them a story then they get into bed I give them a kiss and a cuddle and that's when the trouble begins.

They keep thinking of reasons to get out of bed then the one plays the other up they sleep in bunk beds because of a lack of space but the one on the top regularly jumps up and down resulting in the other crying because she cant get to sleep. I tried ignoring them but that doesn't work either the one slams doors and the other throws things so it can get dangerous. I just want them to stay in bed the only way that worked lately was promising they could have a treat in the morning but I can't afford to do that every day.