Who store seed phrases data Seed phrases seem to be pretty secure, approximately as strong as bitcoin private key according to this site https://en.bitcoin.it/wiki/Seed_phrase.

But who store the private key adresses of these seed phrases, I suppose it is the wallet software provider, so each one of these provider have to save this data somewhere, and what prevent them from storing it in clear text and just acting like it didnt know our private key.
who store the private key adresses of these seed phrases, 


The private-keys are generated from the seed-phrase by a mathematical function. There is no need to store a list of seed-phrases and corresponding private-keys.


  I suppose it is the wallet software provider


No, you should be the only person to know or store your seed-phrase. Ideally it should not be stored on a computer of any sort. Best practise is probably something like punch it onto metal plates - you can buy letter punch kits to help with this. Ideally you'd provide a few trusted relatives with overlapping subsets so that any two of them working together can retrieve your legacy if an airplane lands on you in five seconds from now.