Mutual wealth benefits Been sending me letters covered in plastic saying i am entitled to win a portion of the prize pool of 40m if I send them $50.00 within 14 days. Labrador qld 4215 Australia

Mutual wealth benefits and payment services international have been sending me letters wrappedin plastic with my address exposed.  They are saying that I a guaranteed to win a portion of the total prize pool award mony whether it is $40m, $20m,$1b, etc. Etc. If I send them my payment of $50.00in a form of credit card, check or money order.  I have sent them some monies totalling over $600.00 on credit card and money orders.  They are still sending me the same letters over and over that's when I realize it was a scam.  How do I tell them to stop and can you investigate?