HDFC Bank — I have paid the minimum due twice by mistake one via netbanking and one through autopay system.

Address:

6/50 Chandrabhaga housing,new vadaj

I have by mistake paid the credit card bill for the month of may twice once through netbanking and another through autopay system though i was unaware that after paying the bill the autopay system will again credit that amount. I have tried to call on customer helpline numbers but it's useless nothing has happened i also visited the nearest branch they told me that refund will not initiate.
Please help me in this issue.