Why has my position closed at a different level than my requested Stop or Limit?

Sometimes it is not possible for your stop or limit order to be transacted at the exact price you have specified. This may happen when the market moves very quickly or is very illiquid. In these cases, your order may be transacted at a level worse than the one you have specified. The difference in levels is called 'slippage' and will be determined by us on a fair and reasonable basis. 
Please note that, unless agreed, Stop Loss and Limit orders are not guaranteed.