ok - got a bit further.
i got rid of the unwanted link by turning off the switcher link option in the plugin settings. i the added the following code to my themes footer.php :
<a href='?wpmp_switcher=mobile' onclick='document.cookie="wpmp_switcher=mobile;path=/;expires=Tue, 01-01-2030 00:00:00 GMT";'>Switch to our Mobile site</a>
which gives me a switcher link centered in the footer
however, disabling the link in the plugin settings removes it from the mobile site, so there is no link to switch back to the desktop version. i've tried to put the following code into footer of the mobile theme, but this had no effect:
<a href='?wpmp_switcher=desktop' onclick='document.cookie="wpmp_switcher=desktop;path=/;expires=Tue, 01-01-2030 00:00:00 GMT";'>Switch to our desktop site</a>
so - where can i put this code in the mobile theme to give me a working link back to the desktop version?