State Bank Of India [SBI] — Being charged huge amounts even after paying and receiving unprecedented calls from recovery agents even when there are no dues

Last month, my payment due date was 22md August, I paid my dues on 23rd August at 12:30 AM. They charged more than Rs. 1400 as late fees for being 30 minutes late after 12 AM at midnight. This was never the case before. I have been using SBI credit card for 6 years and always pay on time but failed once or twice earlier and paid the next day or a few days later. They never charged late fees like this. They did this month and that too. I already paid more than 90% of September's due on 4th September, my due date is 22nd September, which means I paid 18 days in advance. They still deducted Rs. 1400 as late fees.

If this the case, and they have started charging fees like this, then this is purely exploitation of their customers.

They have started to charge huge amounts recently and every month, more than Rs. 3000 is deducted when my EMI is Rs. 4800. On top of that they have started to exploit customers with such huge amount of fees. This is terrible for middle class people like us. It's affecting my mental health badly.

Also, SBI card recovery agents have been calling and contacting via WhatsApp even after all dues are cleared and no EMI left to pay before next billing date.
They literally call incessantly and disturb during work and now they started messaging on WhatsApp, even when all my dues are fully paid till date.