Just got a duty invoice from FedEx today, about 2 weeks after receiving the item! Thought I was home and dry. £18.
I used lots of warm soapy (dish soap) water to degrease the car. The tape they gave me wasn't 3M but I'm sure it's a Chinese clone. Acryllic double sided. Seems well fixed although I'm not going to try and get it off at this early stage. Added as much tape as I could to be certain it stays put.