Ola — being charged for the same ride twice

I booked a ride on 7th September, 2019 at 12:34 PM for my mother. She paid the whole amount (Rs.285) to the driver in cash after ride completion. Ola started texting me everyday recently saying that the amount of that ride is due in my Ola postpaid.
I generally ignore Ola's messages and emails as they are generally about offers, etc. but one day when I checked their message (6th October), I thought that they have made a mistake and I emailed them (image 1).
After that, I checked my Ola account postpaid page and saw that they have added the amount in ola postpaid.
I have told them again and again ever since (images) to talk to the respective driver in this case rather than spamming me with messages and emails to pay the due amount that is increasing everyday as they are applying late fee charges.
They are telling me again and again that they are being unable to validate the details with their partner and that I should have reported this issue within three days of the date of the ride. I always pay for all the rides in cash and therefore I do not check Ola's messages and emails and thus I did not even come to know about this issue up until recently.
Only when Ola started messaging me daily on my phone regarding the due amount did I observe that they have added the amount of that ride as due in my Ola postpaid.
If they would have stopped Ola service for me the next day itself (8th Sep), I would have come to know about the issue immediately and would have reported it within 72 hours.

They are spamming my phone with messages and emails everyday now to pay the due amount and it is very annoying. Above all, they are not letting me book any other ride now until and unless the due amount gets cleared.
Why should I pay for the same ride twice? It is Ola's shortcoming that they are not being able to contact and get details of the cash payment from the respective driver.

I want Ola to stop spamming me with texts and emails for clearing the due amount and also to clear the due amount from my Ola postpaid as the rider had paid for the ride in cash.