cheque cleared before the cheque date

I issued a cheque no, 353513 dated 20/4/15 of Rs. 7735/- of SBI to third party. but the bank has debited the amount on 8/4/15 i.e. before the cheque date. I made a complaint vide complaint no. OP1348417703816 on the same day but till date the issue is not solved. I contacted my bank branch but no reply has been given. My contact number is 9582221923.