Tesla customers in California and several East Coast states sued the company over what they called unexpected and steep price hikes for the company’s Solar Roof product.

Chief Executive Officer Elon Musk first unveiled the Solar Roof idea in the fall of 2016, weeks before Tesla acquired solar-panel installer SolarCity for about $2 billion, a controversial move that has been challenged by shareholders.

In early April, Tesla increased the cost of the Solar Roof by substantial amounts —in some cases, by more than 50% — after buyers had already committed to expensive preparation work, according to the complaint filed Monday in federal court in Northern California.

“After completing the sales agreements, and while the consumers have been making plans for the installations, in classic bait-and-switch fashion, Tesla is now informing these consumers they must pay upwards of a 50% price hike on the cost of the Solar Roof if they want to proceed with the installation — and if they do not pay promptly, they risk losing their place in line for installation,,” according to the complaint. “This is nothing short of a deceptive and unfair scheme.”

Musk acknowledged that Tesla raised the price of the Solar Roof on the company’s earnings call last month but said that demand for the product “remains strong.”