Question for Ghana Commercial Bank Ltd. GCB Bank Accra

Dear sir,
I have an global transaction i received mail from the manager Mr. paul that I have to pay the demur rage amount ******** dollers balance to pay to bank, i want to know why they are asking money that i paid before,they are saying not get receipt for this payment, same this append before that time I trust him but i want to know why they dint give receipt.