Contact Orange again and make sure you have a full BlackBerry data plan, not a partial plan like "social networking". The data plan must be a full BlackBerry
data plan in order for things like email and internet to work.
Because you bought it used, the previous owner might have used it on a corporate BES. If so, there may be an IT Policy that restricts what you can and cannot do with this BlackBerry. Remove IT Policy - BlackBerryFAQ