Generic drug maker Mylan Pharmaceuticals faces dozens of questions from Senate Democrats in an eight-page letter questioning whether the company’s response to severe price hikes for EpiPens are nothing but a “complex shell game.”

The letter from 20 senators to Mylan’s CEO shows much skepticism from Democrats over Mylan’s latest move on Monday to sell a cheaper version of the Epipen, which now runs about $600 for a two-pack of the life-saving allergy treatment.