Removing cement from a car's paint...

[StatusRed]

I have my offroader (Daihatsu SporTrak) parked at the side of my Mum's house and the neighbouring property has been demolished with a new building going up, as I use this car for offroading at Pay'n'Play sites etc it gets pretty muddy so I originally assumed these splats were mud remanents from under the body getting flicked up after it rained or something, but today I tried with the pressure hose and these splats weren't budging. I then tried to remove with my finger and it was gritty exactly like cement.

Looking at the pattern of the splats it's obvious it came from the building site next door, so I confronted the head honcho who was there with the architect, the architect took my side and acknowledged this was obviously from the building site but the top guy kept saying something about ahh this contains calcium and we don't use this on our site so it must of come from somewhere else.. Obviously total b.s. so I kicked off a bit..

Anyway.... is there a "safe" way to get this cement off and ensure lacquer doesn't come off with it and won't start to rust?

I've seen there's cement removing chemical sprays but I'm worried this is going to damage the paint? An alternative I've seen is using white vinegar to slowly dissolve the cement but it sounds a very long winded laborious process.

Ideally I'd want them to pay for a professional to sort it, but I'm not even sure who would do this work, Chips Away perhaps?

Any advice appreciated, cheers.