I know that our government will propably do noting substantially. It either finds it unimportant to defend the constitutions or is scared from the USA.

But what should it do?

Here are my proposals:

1) We should stop to exchange any kind of data with the US immediately. This would show that spying on friends does not increase the National security.
2) We should ask the United Nations to debate this issue and to pass a resolution to protect data from internet, mobiles etc. I am aware that the US may block any resolution, but I would like to see the discussion.
3) We should start criminal proceedings against those involved in these programs. This means that we should try to get Snowden as an witness. I know that we would propably not be able to sentence anybody, but the inverstigation would bring things to the light and those responcible would not be able to travel to Europe any longer.
4) We should tighten our laws against the storage of data and we should punish any (American) company that does not follow these laws. Sentence Microsoft, Google and others with some billion charges and see what will happen. If we cannot get the US agencies, we can get the auxs.

In case the US government still insist on their programs and does not appologize and guarantees to respect our laws:

5) Stop any meetings about the economic treaty with the US. how could we have an agreement if one side does not respect our laws?
6) Quit the NATO. NATO was planned to be a defensive alliance to protect the free world. Only time one of the allies was attacked was the US in 9/11. Currently we are involved in a war to defend our American allies. Obviously we have to accept the fact that the Americans behave hostile and are more threatening us and our way of life than some fanatic moslems.

Of course the governemnt will do nothing like this. Most likely it will wait until elections are done and change our laws so that the American acticities are legal.