Toni & Guy big barrel curling tongs

I love big, wavy, voluminous hair and when I discovered the large barrel curling tongs to help achieve this, they went straight on my wish list. 

I decided to go for the Toni and Guy ones. I read the reviews on those and the Babyliss and there didn't seem to be much in it.

I used the Hollie Wakeham - how to get big hair like Cheryl Cole video as a guideline. http://youtu.be/TsG8jYK-MI8

I prepped my hair with GHD curling spray, then curled all of my hair, pinning it up as I went. I curled my fringe and put it up in my sleep rollers large fringe roller.

I left it up in the clips for about an hour. It had fully cooled down. Then released the clips to reveal lovely big wavey curls.

I pulled them through with my fingers to shape it how I wanted then spritzed plenty of hair spray all over.

So far so good and pretty easy to do. Now for the downside. This look only lasted a couple of hours at best before all the curls started to drop out. By the evening my hair was practically straight. 

I have no idea what went wrong. Was my hair spray not strong enough? Did I not prep my hair properly? I have done this twice now and had the same problem both times. I curl my hair with my GHDs and Babyliss conical wand all the time and the curls last a couple of days, so it's not my hair type.

If you have any advice on how to keep my curls, please leave a comment below. Would love to be able to maintain this look for a day, or a night out.