From joining bitcoin sites people call you on the phone.They say someone has hacked your Amazon account of such and amount they will say . They are trying to get accounts with lots of money in it so they can get the accounts number and buy bitcoin.It is always a foreign talking person and they want you to open up a app for them so what I would do is don’t link your card till you are ready to buy.Then take your cards number back out of the site so they css add not find any numbers .Thinking your account has been charged 799.00 dollars will make you trip out just saying you better watch out for them.