Using pay as you go credit to purchase riot points

Is it possible to buy this SIM card http://m.ebay.co.uk/itm/181817403413?rmvSB=true&ul_ref=http%3A%2F%2Frover.ebay.com%2Frover%2F1%2F710-53481-19255-0%2F1%3Ficep_ff3%3D2%26pub%3D5574894536%26toolid%3D10001%26campid%3D5336549684%26customid%3D%26icep_item%3D181817403413%26ipn%3Dpsmain%26icep_vectorid%3D229508%26kwid%3D902099%26mtid%3D824%26kw%3Dlg%26srcrot%3D710-53481-19255-0%26rvr_id%3D911469784511&_mwBanner=1&ul_noapp=true and use the £5 free credit in order to purchase riot points effectively getting the £4.50 purchase for only 99p