We have this same issue - started at around 7 months and is still a problem at almost 9 months - long phase for us! DD sleeps in a grobag and I suspect this makes it harder for her to flip back over (as would a wrap) but she needs it for warmth. I don't have an answer for you as we have similar issues here. It will pass, I guess, when they are more mobile (I think our DD is a little slow in learning to fully roll so hopefully your bub will be more proficient by 9mths).
By the way - I don't like the sound of the wrap that does up around the tummy - sounds to restrictive (amost cruel) to me. I would prefer to have disturbed sleep than to keep my child tied still!