I have passed this level just now on my 6th try, I’ll tell you how I did it.
You have to combine 5 pieces to get those Rainbow Balls, and then combine 4 pieces near those Rainbow Balls so you can get those special smashers that blow rows and columns - and then you combine the both!
Because remember when you combine a Rainbow Ball with one of those special smashers, all the pieces of that colour turn into smashers themselves and create a lot of destruction.
Trust me, it’s doable. You just have to keep an eye out for any chance to create a Rainbow Ball and then a special smasher near to it, so you can combine the two. I did this 3 or 4 times and that was enough to beat this level.
Also, if you’re running out of moves you can use a flare/fireworks powerup to blow an entire column, although I didn’t need to use any powerups.

Just make sure most charms reach that bucket at the very top on the right-hand side of the screen: avoid breaking pieces under the path of its journey there so it doesn’t fall down; I advise you to only clear candies on the left side of the screen to keep the conveyor belt advancing the charm towards that top bucket in the right. If the charm falls it will be harder to try to “bag” the charm in the bottom buckets, as it usually requires those special candies from the combos. So keep “protecting” the charm as the conveyor belt leads it towards the top bucket. Once it falls into the bucket make sure you clear candies on the right side of the screen, so that a new charm is released on that side nearer to that top bucket. Good luck!