I don't think there is a short form of lady name named Jeff... but there might be hundred and one reasons for this mess up. The person might be indeed a girl who has a guy's name... remember Charlie (which can be used both way).
Also it might be a girl who used her brother's account (hence the Jeffrey thingy)?
Anyway, this is seriously OT. And a thread had already been started in the consumer area, we can discuss tat to our hearts content in that area. Now lets focus on TS's problem.
.... Jeffsephine? ....
Wa lao, how can like that cheat ppl...
maybe TS used to be called Jeff. so before you dealt with TS, TS went for an operation or had an unfortunate accident and became Jessica