Standard Chartered Bank — Misleading customer by acting differently in same matter

Address:

Kolkata, West Bengal

I found below transaction logs in my credit card net banking: 06/04/2015 B2SERVICE TAX & CESS @ 12.36% INR61.80 DR INR61.80 06/04/2015 B2OVER LIMIT FEE INR500.00 DR INR500.00 Previously when my credit limit was low, it didn't allow me to pay over the threshold limit and used to give alert if I wanted to cross the expense limit.Now, I am not sure why this card is allowing me to cross my credit limit without informing me and charging me extra amount.How come a customer can know that bank will accept to cross the credit limit by customer when previously it was rejected several times. Please waive that amount and strictly maintain the credit limit in any concern.