i need help getting an answer where should i start.

On Saturday I went Lake Trafford Memorial Gardens to visit my father burial site and upon arrival I noticed that my family values and items was trashed and pushed aside and someone else tombstone has been place on my dads final resting place. I been visiting this grave since once a week since my father died in 2009 and to com this week and see that,and know another family is vising this same location mourning they love and leaving there values and flowers really hurts.. Not know were my father remains are😬