I hired Global Visas in 2008 to obtain a VISA to stay in the UK. Included in their fee (that I paid up front) was the 400 pound application fee for the home office. I was assured that I would get this part of my fee back if they did not submit an application for me. Despite not submitting an application, and months of communications with Global Visas, and reassurances they would refund the 400 pound home office fee I didn't receive a single cent.
In addition, prior to hiring Global Visas they assessed my details (on a proforma they asked me to complete) and assured me I would have no difficulty getting a visa. Within a very short time after taking my money they told me that I would not qualify for a visa and submitting an application would be a waste of time.
Steer clear of Global Visas. They were the cheapest option available, however I haven't heard a bad word about their competitors.