Nash you could try Environmental Services @ South Lanarkshire, here is a link.
https://www.southlanarkshire.gov.uk/...ental_services
If anybody sees a dog owner who doesn't clean up after his or her dog and they can identify them, they should report this to Environmental Health or the Police. The Dog Fouling (Scotland) Act 2003 has made it an offence not to clean up after your dog in any public place, with a fixed penalty of £80.
I suspect the police could get out this by saying this is civil matter due to it not being on public land, but saying that you could also try them but I reckon the police would only do something if this was a public area.
If I were you I would phone Environmental Services at South Lanarkshire Council.