AA Gas cannot get it right

I am being billed for a call-out which was specifically for a water leak in a gas geyser, but it could not be attended to due to bad planning, even though the request was specifically to fix the water leak and the make and model of geyser was asked for before they sent someone out for the call, so they should have had the required parts. As per the report on the bill, the leak was not fixed! They said they would return with the correct parts and fix the problem. Still waiting over a year later, yet the invoices just keep rolling in despite me sending emails detailing my concerns to about 6 different email addresses. Actual quote from invoice: "Check on Totai 6Lt Gas Geyser - leaking water Unit needs a new diaphragm and ferrel - parts not available"