Specific Gravity varied widely after topping up.

If they are only 9 months old they should have a lot of warranty left. Batteries die or commit suicide but most often are murdered by poor maintenance. That said I have seen brand new 1 month old batteries fail. It seems you have given it all. Sounds like you just need to sign the final directive and pull the plug. NO ONE really buys batteries. WE ONLY Rent them for a time.