We had one, purchased it when preg with DS. Got rid of it about 2 months after he was born. Waste of money to buy, one of those needless items that you purchase as it looks good in the shop!

I found that I used heaps of the cassette as I kept on emptying the bin before it was full. You push a nappy in, twist the lid and then it seals in the nappy and the germs. Then you push the next nappy in, and it make like a long sausage of wrapped nappies in the bin.
I found that I wanted to empty the bin more often than you are meant to so I didn't have dirty nappies in DS's room. I was emptying it a couple of times a day (we all know how many times a day a newborn has nappy changes!) I found you can still smell the baby poo smell through them, spraying glen 20 around still did not make me feel it was hygenic - Although many would beg to differ and say it is hygenic, these were just my feelings.

If it were me, I'd return it get your refund and spend that money on nappy sacks. I much prefer putting a soiled nappy into a sack and into the outside bin. Fresher house for all that way!