Hdfc Bank - ATM Debit Card amount deducted twice

My father swiped his ATM/debit card of HDFC bank in a hospital in Dombivli (Dist: Thane, Maharashtra) to pay the hospital bills. The first time the POS terminal didn't work, no receipt came out. So, he swiped in the second POS terminal and it worked properly, the receipt came out, the bill was paid. A few days later we checked our HDFC account passbook and found that amount was deducted both times (Rs. *****).
So, we asked the hospital for a refund. They checked their bank account statements both POS (Bank of India and Allahabad Bank) and found that amount was not deposited in any bank (even once).
We launched a written complaint in HDFC Bank, Dombivli (East) branch with the help of our Relationship Manager, but recieved email that transaction was successful both times. We submitted all proofs (our bank statement, statements of both POS, statement of both hospital banks) but of no use.
Then we escalated this issue to the grievances redressal (support) of HDFC bank but we are receiving the same response for the past * months.
It is almost more than * months now same email communication is going on.

*. HDFC Bank does not have any phone support to resolve this issue.

*. We have launched an online complaint with banking Ombudsman (but have least expectations from them).

*. Launched complaint on consumer forum, they tried to resolve but received the same response from HDFC support guys.

*. Our next step to take this issue to consumer court.

Location of the hospital: Dombivli (West).
HDFC Bank Branch: Dombivli (East)

Date of transaction: **, Nov, ****
Transaction amount: **,*** (two times)

We are completely fed up and drained by the attitude of HDFC bank. They are saying that transaction was successful both times but then how it is not reflected in customer accounts? Why don't banks have phone support for such important issues?