The idea as such is not new, e.g., Lufthansa has been doing it for a while for SEN's that do not requalify (although I fail to understand who would pay EUR 2000 for a 12 month extension...). However, I agree that it is somewhat suspicious that they would call instead of providing a payment link like others do, but then again, if they call the number on a Skywards profile that seems pretty secure. Anyway, a call to EK would authenticate.