Since no one answered you so far, I'll give you my 2 cents. Basically, Exchange is related to Microsoft account, if you have one. For example, I use Exchange services for email, as I work for a Microsoft partner and we use Exchange. You probably have an exchange account set up, otherwise there shouldn't be any data traffic on this. Also, since I use it for email, the regular monthly data traffic for me is on average 100-300 MB, and I'm really busy, so something is seriously wrong with yours... Maybe you have huge attachments and you set it up to download them automatically. Or simply disable automatic sync or completely delete the account, unless you really need it, but I'm guessing you don't...