I already checked my all purchase history and i dont know what I have been charged for amount RM15.80

This is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. See each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' on your billing statement - Apple Support

or go to Subscriptions and Billing - Official Apple Support

If you're sure that those charges come from Apple (check your bank statement very carefully, ignoring scam messages that might be addressed to your iPhone), start reading this support page:--> Subscriptions and Billing – Official Apple Support, and check each of the first 3-4 sections.

If you cannot find the information you were looking for, please contact iTunes Store Support Team directly and explain your problem, using this specific link:--> Apple Support

Regards

Giulio