I am on the same package with Orange as you. About a year ago I contacted them to see if I could change to Home Starter. It appeared that this was not an option, but I indicated that I was not at all happy and would consider changing to another ISP.
At that I was told that, as a good will gesture, I could have mu current packageat 6months free and then the next 6 months paying �17.99 a month. It did tie me in for a furthar 12 months, but I diid not mind and really did not want the hassle of changing ISPs and, in effect, got my broadband for a year at the same price as Home Starter.
Could be worth your while trying the same ploy to see if it works for you.