Sleeping bags to tie to cot???

Hi
My baby can now turn on her belly but not vice versa. This leaves me with a screaming child in the middle of the night who needs turned over again. I know that when I was young there used to be these sleeping bags that you can tie to the side of the cot so the babies would stay put. Does anyone know if they are still sold somewhere? I have tried tucking the end of the sleeping bag in under the mattress at her feet but she still manages to turn around.

Katy and Ashira 19 wks