You show the police report to Grab or merchant ?
both but doubt it was of any use to Grab
in my case the merchant was some large gaming credits company, found their email and sent them the fraudulent charges + police report - they should know better that chargebacks cost them arbitration fees, so they located the txn and refunded me instead of having to go through the entire process
there's no point telling Grab, they won't refund. some merchants know it's not worth it to fight the chargeback esp if you show them police report because of the fees involved (can be up to $100), so it's always better to look for the merchant if you can (esp if you can find their contact). if they refuse, then go ahead with chargeback through your card issuer lor