This does sound very shady.
How did you get the phone number you called?

There is a increasingly common scam where scammers setup fake websites that look like official airline websites. The phone numbers on these fake sites lead to scammers.

If you have inadvertently called one of these scam numbers, they now have your PNR and can make changes. If this has happened you should contact TK and see what they can do to secure your reservation.