Very disappointing - hard to use

I highly recommend this product! I have managed to use that sometimes, then, impossible to block. The locking key is twisted in the bag. I tried to have a support service but the number never answers and there is no possibility to contact someone on the site. The manual is no help. I preferred to give up and move to a newer model in Kensington, where the cable clips onto a tiny device which is fixed directly on the computer. It is the day and night.