State Bank Of India [SBI] — service charge on debit card

Address:

Palakkad, Kerala

I used my SBI debit card for filling petrol from Murughan Auto Fuel Agencies on 10/12/2017 for Rs. 2000/-. On 12/12/2017, a debit of Rs. 50/- was seen on my account and shown as surcharge on fuel. Whereas, there is no surcharge for refilling in petrol pumps. I get a .75 % incentive from other petrol pumps. When inquired about the same to the fuel agency, they give the reply to contact the bank. The POS machine installed was of Lakshmi Vilas Bank. After giving complaint to SBI, after two weeks, no reply was received so far, nor the money was credited back to the account.
Please do the needful .

Thanking you