These places often prey on the uninformed and the 'desperate' - ie 'nothing else has worked for me' which is usually down to poor advice or a lack of knowledge. Claims and results can, in the short term at least, often appear to be dramatic - especailly when the person is severely overweight (obese). In these cases a simple change in the persons diet and and starting any sort of exercise will shed a lot of weight (note, 'weight' not just fat - as a large amount of this weight loss is water). However, this rate of loss is not sustained for very long, and more often than not it stops before the person has reached their target weight. The result of this is that that person will often feel dissapointed and lose interest as 'it's not working anymore', return to their previous eating habits and put the weight back on.
The techniques described by previous posters, such has 'tummy massage', sit-ups on a pilates ball and such like are not very useful at all. The only way to loose body fat is by creating a calorie defecit. Most important in this process is your diet, followed by your exercise routine and then your daily habits (ie walking up stairs instead of the escalator etc). Somebody massaging your stomach is not going to help, additionally the amount of sit-ups required to burn a 1lb of fat (thats 3500 stored calories) is in the thousands.
My advice, save your money - sort out your diet, and start a proper exercise programme, involving resistance training, high intensity interval training and steady state cardio - and increase your Non Exercise Activity Levels (stairs, walking, etc) in that order of importance.