Private Health Insurance

Last week, August 8, the company I work for held a 'seminar' for a health card, which will be provided by IntelliCare. This is new to us, as the company has never offered us health insurance before. There was quite a heated debate as the Q&A is on-going, as we found out that there are a lot of uncovered illnesses, and the company's share for our premiums is not explained clearly. Also, some of us are already paying premiums for another health insurance company. They didn't even distrubute a brochure for the health insurance. Yesterday, we were told that this will be mandatory, even without us signing for anything. We actually refuse to sign up for the insurance as we think it won't be beneficial for us. We were told that starting the end of the month, our salaries will be deducted based on the badly photocopied 'contract' that they distributed (which also didn't elaborate which are covered and what are not).
My question is, is making this private health insurance mandatory, legal? Do they have a right to force us into paying the monthly premiums for IntelliCare? As far as I know, only SSS and PhilHealth is mandatory for private workers.