The freezer part of my Liebherr KGNves 3866 has rather suddenly stopped reaching the set temperature of -16. This happened after a relatively quick thaw caused by not shutting the freezer door properly. Since that time about 3 weeks ago it has only reached the set temperature once. The temperature then rose after I added some items in the freezer and now struggles between 0 and -9. Tried the obvious of cleaning, defrosting and restarting again without much satisfaction. can you please help