I have used Dent Devils, not long after I got the Zed in 2008, someone hit the rear wing with their door. That year at the BMW car club annual Gaydon gathering, Dent Devils were doing a special deal for £50 a dent so I gave them a try. the result was perfect.
A couple of years ago something fell of a shelf in the garage and dented the boot lid so I called them. Their standard price was £75. The chap arrived and tried to remove it but it was very difficult due to the double skinning. When he had finished, it was about 90 per cent fixed but he said he couldn't charge me for it because it wasn't prefect.
He left me his mobile number for future use. In 2014 driving past Lake Garda a huge fir cone fell on the bonnet leaving another dent. When I got home I rang the Dent Devils man who came and removed it as an unofficial job for £20.