Can't send Lithium Ion Battery to overseas from Australia

Recently I sell my mobile phones via ebay. I though the posting was simple, just drop the item to post office but apparently they don't let you send battery to overseas >.< So I seek other alternative way to send the items. Called DHL, Australia Air Express, FedEx and UPS when I said I'm sending a mobile phone with battery to overseas they all reject me saying it got to do with IATA regulations >.> At this stage I was so pissed because I need to refund the money and waste money from ebay fees. Luckily I found a courier that send battery ^__^ which also cheaper from those company I called. The courier called PackSend (http://www.packsend.com.au/), I would recommend for anybody who want send battery to overseas from Australia.