Question: suspicious emails asked me to pay the iTunes bills i never purchased
I received a suspicious email on 31/12/2017 stated that my acc was logged in other device and made changes to Shipping and/or billing details. So it said for security reasons, they had locked my acc. In order to continue using my ID, i had to login and unlock it using the link. I did not do anything bcoz i had suspected the sender.
Then i received another email on March 7, 2018 stated the same reason and i again ignored it.
Today (March 13, 2017) i received email from AppleID Service and it is said to remind me to make a payment which is $75.96 for "Gift Card iTunes $70.00" which i never purchased. They even have a "login account" link but i never tried. They also have a statement that "If u did not request this change, please notify us immediately by e-mail at firstname.lastname@example.org". I almost sent an email to that address and realised that i should do it here instead.
What is happening to my AppleID? What should i do next?
iPad Air Wi-Fi, iOS 11.2.6