The 545's will fix themselves when you log out if you have them equipped. You got scammed. The only way to keep them at that item level is to put them into void storage before you log out. There's a void storage in SW. Also suggest you read coolzos guide before spending a small fortune on bad gear.
The 545s are lemons, if you really did buy some and haven't logged out yet, equip them and put them in void storage before you log out. You want the 515's.
I'm 99% sure the highest level you can toggle chromie time on/off is level 68. I know you cant at level 69.
Keep in mind in dragonflight they allowed 60s to toggle chromie time sometime during the last season. So, while it might not be available now its something i always check on PTR.
As Coolzo pointed out they will get fixed on relog if its in your inventory. You can bypass this by placing them into void storage before you log out.
This comes with some obvious drawbacks as you would need to re-enchant and re-gem everything when you take it back out and hope for no...