Download directed to wrong version

[srdiamond]

Discovering that I had 4.2(a) installed, I wanted the free upgrade to the latest version in the 4 series, I went to 4.2(b) and installed the download, only later to realize that the button to download b downloaded 5.1, which isn't free and I didn't want. But here it is.

1. Why did the button attached to the history of 4.2(b) take me to 5.1? This is irritating and appears to be commercially manipulative.

2. How do I get the version I want?

3. What do I do to install it, now that I have 5.1, which I don't want to pay for? Must I first uninstall 5.1? Will uninstalling it delete my data? I don't need these complications for a simple upgrade.