Former U.K. Twitter employees who were fired after Elon Musk completed his takeover of the company have mounted a legal challenge accusing the social media giant of subjecting them to “unlawful, unfair and completely unacceptable treatment” during the layoffs, according to the report. London law firm Winckworth Sherwood—which is representing 43 of the over 180 British Twitter staff fired in the company’s widespread cuts in November—accused Twitter of running a “sham redundancy process” in a letter sent to the company on Tuesday, according to the Financial Times. The letter warned that the fired workers planned to escalate their complaints to an employment tribunal if their concerns aren’t addressed.