William and Fudge scam???

Hello! I just was wondering if anyone was having this same problem. I recently started getting calls from William and Fudge and they were saying my student debt had been transferred over to them, this made sense to me because I hadn’t paid my school in a while, so i understand why they would send it to a collections agency. But, every time William and Fudge calls me, they’re wanting me to give them my card number over the phone and kind of being rude to me. I asked for them to send me an email about it and they said they needed a reason why I wanted their email in the first place. I said its because im uncomfortable telling someone my card info over the phone. So they said they would but I have yet to get one, and I haven’t gotten a letter in the mail or anything either. Whenever I look the number up, it comes up with the William and Fudge office but everything just feels so scammy I’m afraid to do anything. They called me today, and when I answered and said hello, it was just silence for like 5 seconds, so I hung up. I really have no idea what to do or if I should believe this, has anyone else had an experience like this?