I had the same problem last year on my 2005 385GL. Mobella is a Swedish company based in Eskilstuna. They were acquired by a USA company called Southco. They sell through Amazon. Just search for “Southco Mobella lock”. Their UK site is showing it for just £43.60 today, but they only have 1 left!
I was very surprised to find that the key for the new lock was the same as my old one – not very secure! A Dufour dealer told me that there were only about 7 or 8 different keys for this lock.