Bangalore Water Supply & Sewerage Board [Bwssb] — online payment failed but no refund till date

Address: 507, 80 feet road, Maruti Layout,, Subramanyapura post, 560061

I have made an online bill payment on 29th april 2019 for amount of 6360+gateway charges on bwssb website. The transaction has failed as per the status but the amount has deducted and billed to my credit card.

The issuer bank has said that the merchant has claimed the amount but i do not see that in my consecutive month bill.

The gateway or bwssb have not refund the amount till date. Please suggest further actions to take.