I CLOSED MY ACCOUNT BUT STILL RECEIVE CHARGES EVERY MONTH!!!

I SETTLED THE FULL BALANCE ON MY ACCOUNT AND CLOSED MY ACCOUNT IN JANUARY 2018. EVERY MONTH I AM STILL RECEIVING STATEMENTS. LAST MONTH IT WAS AN ISSUE WITH A MR PRICE SIM CARD THAT I NEVER ACTIVATED OR USED. ACCOUNT THEN CLEARED. NOW TODAY I RECEIVE A STATEMENT FOR MORE CHARGES FOR MARCH??? I CLOSED THIS ACCOUNT!!! FILLED OUT THE FORM IN STORE AND CLOSED IT!!! PLEASE SORT THIS OUT AS I AM NOT GOING TO DO THIS EVERY SINGLE MONTH TO REVERSE CHARGES AND THEN JUST TO BE CHARGED AGAIN FOR AN ACCOUNT THAT SHOULD NOT EXIST ANYMORE!!!