I got unknown billing 5 times for 5$ for each transaction. what's wrong?

my phone is Iphone 6S with an update IOS.

Lately, i always received a billing statement from my credit card with 5 times transactions 5$ each purchasement.

Since I always get notifications from Apple by email for every purchasements, I really have no idea about these 5 times transactions, because there is no notifications from Apple.