It is a good idea to use a registered agent, who will get you the visa as promised. All registered agents have been vetted and authorised by the UAE immigration department to operate in the UAE. They are regulated and they are monitored on an ongoing basis. They must abide by the regulations laid down by their regulating body, which means that they must offer only those services for which they have been licensed and approved. One can therefore be sure that these agents will help you with your family visa application if you pool in enough information before you engage them.