A lot of information can be had (in spanish) at
www.set.gov.do
There is also a termination pay calculator. The minimum wage varies depending on the capital stock of the company in question, but is generally somewhere near 3500 pesos/month, this is based on a 45 hour work week.
There is a small army of lawyers hanging out around the building (depends what part of the country your in) that will help him to get money from his employers, the weight of the law is very much on the side of the worker, right or wrong the worker wins more than 80% of all cases. Most employers will opt to pay right away if they feel the case may go to court, since they will have to pay heavy court costs and other settlements if the case drags on, and they know they have very little chance of winning no matter what the situation.