If somebody else has your card details, a Now membership, even a Sports one, is the least of your worries, and you need to get that card blocked, and replaced with a new one, ASAP.
But do they really have your card details, or is it just that you have made available a Now device with your account open on it, and you haven’t set a Payment PIN?
e.g. a shared TV; or even a device with Now open on it that you have disposed of without Factory Resetting it?
Yes, I know; my reply, as per the @, was purely aimed at BangBang2112‘s particular circumstances.
Staff with staff via live chat by clicking “chat online” within the green box. Don’t hit “get help quicker” as this is a bot.
Another user was having issues with live chat on Firefox and had to switch to Edge in this thread