I've had a reply from UK support giving me a link to a site called NextBase Parts. I've found and ordered both a self-adhesive mount and some spare sticky pads. For anyone needing these they can be found here.
If all else fails, purchase industrial velcro. See: https://www.amazon.co.uk/gp/B01M8HOUG9
Just be aware, it is so good, it can be difficult to separate the two different hook and eye contact surfaces. I have been using the product for years. In fact, I have a reel of it and it can be used for many things such as suspending tools: https://www.amazon.co.uk/gp/B00186Q7XY
Indeed it is a better solution than the original mounting system on my SpeedCheetah C 550.