wrong number?

Left message saying they were trying to reach me about an important matter from wamu card services of which I have NO credit cards with. left 800 #. when I call it, it keeps asking for the last 4 digits of my credit card and nothing else

763-892-0014 is for WAMU

Caller repeatedly calls cell, no message left. Also, when I try to return these calls, get a message saying cannot be called, # may have been diconnected.  

WTF gives? Apparently a lot of other people are receiving these calls; I simply blocked the # on my phone.

Called my cell and left no message