It is important to have realistic expectations when working with migration agents. Even the best immigration professional cannot do some things.
The processing of an immigration application is a time-consuming affair. Professional agent will ensure minimal delays by ensuring proper documentation and by avoiding mistakes. However, no agent can speed up the application beyond the official processing time. Be wary of anybody who claims that he or she can help you immigrate faster than the official time line.
Similarly, every country has its own rules and regulations about inadmissible applicants. Normally, a person who has a criminal record or a person who is a threat to security will not be allowed to apply for immigration. No agent or professional can help you bypass these rules. If you are inadmissible, then you will have to formally apply for an exemption. It is best to avoid agents who claim that they can help you bypass the law.