I recommend doing a software reload or backing up your device and doing a factory data resetThis should workIf you still experiencing this issueI suggest you take your device to your nearest Samsung Service Center for an assessment

Hold on the Bixby buttonIt will take you through some stepsOn how to set it up

Open your WhatsappClick on notifications and check what you have selected for incoming callsIt maybe that the sound is a notification sound repeating for an incoming call

What is wrong with your Tablet

Please contact your service provider and ask them to remove these subscriptions from your accountI'd recommend you contact your financial institution as well and inform them of thisThey will remove it from your bank account