The phone companies certainly have the capability to allow their customers to block numbers. This is an excellent example of why they should enable it.
I answered (unfortunately) and pressed one. A man came on the line and asked me if I wanted to lower interest rate on my credit card. I said sure. He said "you have a card with Bank of America, Chase, or Wells Fargo?" I said nope. He then added a few others to include Capital One. I said okay. He said and your balance is over $3,000. I said are you asking or telling me. He said I am telling you and I said no it is not over $3,000. He said "it is not?" And I said NO. He said okay and hung up.