Which VISA or Mastercard credit cards _always_ ask you before denying
a charge, or immediately try to contact you to let you know there is
an issue?  I have a few cards that deny charges when they see
suspicious activity, but I only find out after hearing from the
vendor, and I have to go hunt down my card company and deal with it. 
I condsider that poor service.  I want a company that places a premium
on good service, and will always contact me so that when there is an
issue, I hear from them before I hear from the vendor.

I seriously doubt whether there is such a credit card issuer and I
suspect that whether or not you get called depends on a variety of
factors, including your own contactability.

One solution may be to carry two different cards with the reasonable
expectation that if one fails the other will come good.

Of course, if you were to manage your account more systematically then
the credit card company may only contact you when it's checking to see
if you are the legitimate card holder.