As someone who fabricates custom stuff for a living I understand sometimes things just get screwed up and its hard to eat the cost. Parts damaged in shipping/storage, bad employees, tooling breaks, simple human error. But I would never lie about something or make excuses, I've had things over the years that weren't 100% perfect when finished but I always tell the customer what happened and offer a major discount and if they aren't happy it's time to suck it up and start the project over. Obviously your not happy so I would ask for new tanks. What they do from there will tell you exactly what kind of business they are.