Apollo Clinic — Incorrect billing and refund issue

I had visited your clinic at HSR layout, Bengaluru on 9 April, 2022 for my mother's knee problem.
I was asked to take an x-ray and the billing person wrongly billed it. As i noticed the same, i checked with the doctor and the technician and I was right.
Therefore when the doctor asked the billing person, she said it was done through your system and it was a technical error.
I was asked to wait for a day to get my refund. Then i was told a week and further next Monday. After 2 weeks i was asked to come and collect the refund as it won't be credited back to my account.
I visited twice to the clinic and was sent back saying they are not aware or the cash wasn't with the person at your reception.
It is 3 months and even now they are saying 1 day, Monday, next week..
Your accounts person confirmed she'll update me in a day and it is already 3 weeks again.
They have just wasted my time in the past 3 months.
They have collected my original bill and given a new bill in which it says my payment is settled.
Totally unacceptable response by such a big network of hospitals.
Above all, the treatment was it no use as her medication didn't help the diagnosis.