Exactly, the problem is "oversight", particularly about how the collection of data is processed and what is being done with its output.

Overall oversight (and not particularly on this subject) seems not be working very well in the US, is completely dysfunctional in ICANN and nonexistent in the UN, and in some particular where it does not exist at all, surveillance is used for the political benefit of the party in power to control, suppress or limit its opposition.

So the question is, who is qualified to establish a supra national organization to oversight ? not ICANN, not the I* orgs, not the ITU, who ?

While intelligence agencies and organizations keep getting the mandate and funding, they will continue to do what are they doing and trying to scale and improve their capabilities, and there is no international organization or forum that will be able to change domestic policy.