A year ago, the Juicero juicer seemed like a must-have product for health nuts, but now customers are demanding their money back.

The Juicero was pitched as a high tech version of the traditional juicer. Using a "4-ton" vice, the machine would "cold press" special bags of juice made by the company.

While the appliance cost $700 at first, the price was lowered to $400, and global tech giant Google believed in the invention enough to invest $120 million in the company.

But there was one problem: the machine is basically useless.

The news outlet Bloomberg were the first to realize that you can just hand-squeeze the packets. The old fashioned method even makes juice faster than the machine.

While the Juicero can connect to the internet and an app on your phone, it turned out that the "400 custom parts" customers were paying for didn't actually do anything.

Bloomberg first heard about the truth behind this machine when some of the company's own investors complained that it was pointless.

But when news broke that the juicer was a waste of money, Juicero reacted in exactly the wrong way.

Click the next page to see the CEO's strange reaction.

In a bizarre open letter posted online, Juicero CEO Jeff Dunn complained that customers "hacking" his product by squeezing the bags were missing the point.

He says that the "experience" of the machine is what really matters, along with a handful of extra safety features.

The Juicero can scan special codes on each bag to check if they are expired, or part of a recall, but the expiry date is also printed on every bag.

In the strangest twist of all Dunn linked to his own video, of Juicero's communications head Chrissy Tramedach cutting a Juicero bag open. It's not clear what exactly this was meant to prove.

Juicero says it will offer refunds to any customers who want them - even if they paid full price for the machines - but maybe some customers will be happy to let their Juiceros do the hard work.

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