Of course, in reality phone company's exchange the right to monitor what you say for common carrier status which makes them legally immune to the fact you are saying it, and credit card companies do in fact ditch whoever they want because they have no such burden.
The solution in one case is obvious (protect net neutrality) and the solution in the other case would line up with the calls for US Post to be extended to offering basic banking services to ensure an appropriate floor on the transaction market, and as a government entity would have to allow everyone to transact.
It's not clear to me what you seem to think Google, Twitter or Facebook should get in response for becoming a "public plaza" style arrangement which would be detrimental to their business model and wouldn't destroy the rest of the internet in the process? After all is a DDOS attack also free speech? A botnet? What are we going to obligate them to carry and on what basis?
The two major credit card companies that dominated could have canceled anti-war "haters'" credit cards in the name of patriotic support of the just cause, banks closed their checking accounts, the major airlines refused to fly them, and so on, and those on the left with your principled commitment to the right of "monopolies and near monopolies" to enforce their political preferences would have had no major objections--as long as it really is a general principle and not just a pretense.
Is the government or some other absolute authority censoring wrong? Yes. Are powerful monopolies (or near monopolies) wrong to censor? No, because they have the same speech rights as others
And yet I suspect that this support for the "freedom" of the most powerful to silence, control, and enforce their will is not really the general, politically neutral commitment to everyone's freedom of choice that it pretends to be.