If i understand your question, you can do step chart with a line chart.
I do an example in attachment. I hope that can help you.
Step_chart.qvw 155.0 K
Many Thanks Rod, that was a lot easier than I imagined, I changed the display options in my chart to Plateau (trailing) and I almost have the visulisation I need. The other feature of the step chart that I am looking for is the dimension axis that acts as a time line so that we can see the period of time between each price review.