Stick with no more than 25% changes IMO, but you can do them either daily or every second day. If you shock the corals, you will probably lose most of them. Nothing good ever happens fast.
And they aren't in Toxic conditions, just far less than ideal. There is nothing toxic or deadly, you just need to gets the levels back to where they should be..
Pull 25% out, put about 15% NSW and 10% RO back in.
Check the levels.
Repeat the process every day or every second day. Things will be back to where they should be within a week or 2 at most.
Whatever you do, good luck.