That’s still sounds very very odd that they would tell you that. We have a few large format printers. One of which is a HP DesignJet 800ps. It has four colors and it uses the ink pretty much to the bottom of the container. It gives a warning when the ink hits around the 25% mark, but it will still print until the ink has run out.
I don’t know if you bought your printer directly from HP or from a re-seller. You should get this resolved before your warranty runs out though. It almost sounds like they are trying to put you off to avoid dealing with it long enough for it to be out of warranty. I would badger the h e double hockey sticks out of them. Talk to a supervisor at HP if you have to.
You should record the conversations you have with the support people for a legal record. Obviously written correspondence is easier to keep track of. I know here in America legally you must make the other party aware that you are recording a verbal conversation. I know it sounds a bit horrible to have to resort to that, but it seems as if they aren’t being totally honest with you.
I don’t know if the printer has a Fiery or what kind of RIP that it’s using, but it could be some other hardware / software problem. You should up date all of the software that you can (drivers, OS, firmware, RIP etc…) to see if that might resolve the problem. We had one printer acting funny, come to find out the machine with Windows on it was not updated. After updating it solved the print problem. Also it was recommended to us to change the print heads out for about every 10 (total sets that is) of print cartridges being changed. I might recommend having a service technician take a look at the problem. From what I’ve read that HP printer pretty is highly recommended. It’s better to know earlier than later, for the money that you’ve spent, if you’ve gotten one with a hardware problem. Good luck Chris. I hope you get this sorted out.