"the installed product does not match the installation source(s) error when uninstalling a windows service"
The issue here is that you are trying to uninstall a program for which the original installation source has either been deleted, moved or altered. In short, although the program you're trying to remove has a PackageCode ( GUID ) X, the msi your machine is trying to use to remove the program has a PackageCode of Y.
In order to resolve this, locate an MSI which is similar to whichever program you are trying to remove, then run:
MsiExec.exe /I example.msi REINSTALLMODE=voums REINSTALL=ALL
Once this command has completed, the MSI will be effectively re-cached with PackageCode Y.