If Airtel Calls You from Delhi but the Number is Registered in Mumbai — What Next?

So, Airtel calls you from Delhi claiming you've a pending bill of 10k. But, on checking the website, the mobile number is registered in Mumbai. You know you haven't been in Mumbai in years. What do you do? Do you pay the bill, report the fake call to the police, or do nothing? If you decide to pay the bill thinking it's a genuine call but later discover it was a fake one, can you claim the money back under the Consumer Protection Act? Would the police even bother to investigate or would they just tell you to be careful? What if Airtel claims it was an internal glitch, would they be responsible for the fake call?