caught by phishing scam on ipad despite high security

hi

ive been using my ipad 2 for many years (8?) and always have it on the highest security settings and have never had any problems or seen any pop-ups. 2 days ago i clicked on a normal link in my facebook newsfeed and i was presented with a page that said 'youve won an apple prize from amazon!' i immediately thought this sounded suspicious even though the page looked very amazon-like. a small pop-up box then appeared that said click on the 'ok' button to say you have read this. there was no other way of navigating off this page apart from by clicking 'ok', so i did. the next screen then said 'answer this multiple choice question to get your prize' but i was able to navigate off that screen, so i did, without clicking any boxes.

we have never been victims of any sort of credit card fraud as we are super careful with all our our security but today our bank phoned to say someone had been trying to take money out our account yesterday, but had failed, so they are sending us new credit cards. it is too much coincidence that ive never had a pop-up on my ipad before and never had attempted credit card fraud and now they happen within 24h of each other! so i believe i got caught in a phishing scam from that 'prize' page.

can you please tell me:

a) how can the phishers have got my credit card details when i didnt enter them on their phishing pages - all i did was click an 'ok' box. however, the credit card details are stored on the ipad (itunes... paypal... etc). thankfully they didnt get hold of the 3 digit security number so couldnt actually get any of our money.

b) how can i have got this pop up when my ipad is set to 'no' for pop ups and ive never had one before? have the scammers found a loop hole in the apple system? i thought IOS was bombproof?

c) is my ipad now somehow infected? if i now put my new credit card details on it will those details be passed to the scammers? how can i check?

thanks