Hi Steven.....welcome to the Forum
Has anyone who has replaced the previous batteries said what was wrong with them (e.g. buckled/distorted plates, low on electrolyte, anything suggesting overcharging such as barrelled casing?).
It could be that they have been using a faulty batch of batteries because unless a battery has been overcharged then generally they can usually recover from discharge and even sulphation with a decent battery conditioner being used to trickle a charge overnight.