Lowering the PH to 7 and aerating is the only way to get alk down. I brought mine down from the high 200s to 110.

I've found that splashing about is by far the best aerator. Works the quickest. If you have kids, put them to work

On the alk, drop ph to 7, test alk, if still need to drop aerate until PH rises, drop back to 7, repeat as often as necessary.

If you bags of shock are dichlor, they'll add more cya. If they are calcium hypochlorite, they'll add more calcium hardness and can lead to cloudy/hazy water. If they are lithium hypochlorite, you paid to much but go ahead and use them If they are non-chlorine, sell them to a "friend"