Gas exits, unfortunately a complete flop!

I bought the device to prevent our cats at night by scratching at the bedroom door. With the motion sensor and the first gas can, we were completely satisfied and could sleep for a month leisurely.
The Outrageous about the whole story, however, is that

1. the price of refill cans, hitting with almost 12 to beech, is really overpriced. The acquisition price of just 30 euros you can get over for the tower yet, but 12 for a bottle of gas is really awesome, especially since these hold only about 1 month.

2. the refill cans are not compatible with the essay previously delivered apparently because the gas escapes unhindered. You can hear a distinct hissing. Apparently this is not an isolated case, as one can see in several other reviews. Should I buy a whole new set of motion every month? Why can not the manufacturers do not manufacture compatible adapters that hold the expensive gas in the cans?

I am extremely disappointed to have bought the product for so much money, that keeps its promises only prima facie. Too bad, because it would work with the refill cans as it should, I would get over the high price ...