If your control is in a SharePoint web part you need to run something like this:
SPSite site = SPContext.Current.Site;
SPWeb web = SPContext.Current.Web;
using (SPSite ElevatedSite = new SPSite(site.ID))
using (SPWeb ElevatedWeb = ElevatedSite.OpenWeb(web.ID))
string path = Path.Combine(basePath, NewFileName);
Despite of what Telerik people said, I couldn't make it run without elevated privileges.And on the target folder , the user under the application run (application pool user) should have read/write permissions on that folder.