I was hired around 6 months ago at a call center. They have just, without my consent, and in fact I had communicated clearly that I did not want to do this, signed me up for a course to take different kinds of calls alongside the ones I'm already taking. there will be no increase in pay. I communicated clearly to my supervisors boss that I had no interest in increasing my job responsibilities without an increase in pay as well, and I was told essentially tough shit.
is this legal? can they add to my responsibilities without increase in pay?
for reference I live in MA, USA.