Hi,
Sorry we haven't got back to you since you last wrote. As far as I can remember, getting a second letter from Platte is not unusual (if they have your address, of course), but we've also not heard of anyone actually being taken to court over non-payment.
SwampyUK's story is probably one of the longest running, you can read the start of it
here and also more
here - as you can see, threats from Platte but no action.
Perhaps others with direct experience of having contact from Platte can offer some more solid advice?
Update: I've just read ForumFriend's reply, hopefully you'll find the personal email.