You can use both. The astute students and parents (consumers) should be more concerned about whether the agency is authorised (by the target school/college/university) or not. Not being authorised does not necessarily mean that an agency is bad. It just means that the consumer needs to assess it with open eyes as to pricing and competence. Some non-authorised agencies can be very good.

Peter, if you would like to improve your English lon this platform, we would be happy to help. If, however, you intend to ask members here to edit the marketing literature for your business, then most of us would not be so willing. I think you understand why.