Did you pay it off every month? If so, it could be that you are one of those customers by whom they
lose money.
There is a name that CC companies give to folks who pay off their balances every month and I can't recall what it is, but there is one. Like for me -- hubby and me never carry a balance, we have no annual fee, and yet we earn miles for every purchase - hence, we're a CC Company's nightmare bc they lose mony on us.
Anyway, maybe it's that? Why on earth could they not tell you the reason? I think that's terrible!