Loud neighbours/unsupervised children.

Hi.

We’ve been experiencing lots of problems with our upstairs neighbours regarding noise, water and dirt thrown into our balcony, parking right at our parking spot… we reported it to their Property manager and ours (both renters), and so to the secretary of the committee as the chairman doesn’t live here anymore. Apparently lots of ‘complains’ have been sent to the tenant upstairs, who now seems to be doing it all on purpose. Our agency says ‘there’s not much they can do as this is a Strata issue’ – Strata manager told us we are not to contact him directly.
They also let their boys (4 and 6) run around on their own in the parking lot, common stairwell and front door. My partner almost reversed into the little boy as he came running towards our spot.
What can we do? I am not sure a notice to comply has been issued only informal ones.