The unattended waste disposal issue in Kolshet near Devashree Park is a serious concern. You can report this to the Thane Municipal Corporation (TMC) through their helpline: +912225331590 / 18002124530. Additionally, you can raise a grievance via the TMC Swachhata App or visit their website for direct escalation. Since waste buildup poses health risks, you may also approach the local ward office for immediate action.