Val, your correct in your statement, the order didn't go through as a limit order, if it did I can't see that they could open it at market.
What had happened was I placed the order the night before, in the morning before start of trade I cancelled that trade and opened a new one with the prices I quoted in my first post.
I didn't realise it at the time but have now discovered what happened. I filled out the order form not realising that after I entered my opening price ig's system selected the order type, and it selected stop, I had selected limit the first time the night before, and in the rush to get my order in I didn't see the words stop instead of limit, I read it over two or three times but only saw my prices I guess, checking that I had them entered correctly, more care was needed.
As I said from the beginning it was my fault and it was a lesson I learned the hard way, with my money, what sort of annoyed me was that they placed my order at the exact same place where the stop loss was going to be triggered, maybe just bad luck, I know that in saying this I am assuming that they already knew the low and thus knew where to enter me as to trigger the stop loss, but then with the time delays and the way computers can be programmed who knows.
The lesson here is to be sure of everything before you hit that enter key or click on that submit square.
