I found a Stoplock easy to use for the period I owned a Golf GTI. I can understand your worry about theft. At the time I followed the Golf GTI forum and there were regular posts of break ins to homes to steal keys, one extreme incident when a family was threatened. This was a contributory factor in deciding to part company with it, just didn’t want the worry (plus local VW dealer was appalling).
As previously pointed out, the Jazz is not a “desirable “ car for performance freaks, or simply steal just to resell. Not enough of them around. Keep your keys in a Faraday pouch or disable keyless entry and sleep peacefully at night!