Whirlpool Freezer WVE1882A stupid failure

Whirlpool Freezer WVE1882A+NFW
My Whirlpool WVE1882A+NFW Freezer (European 220V model) was making some wheezing noises, gradually the temperature was rising from -23 to -10 in a 2 day period. That made me very suspicious that something happens and I removed all food to another freezer. The temperature kept rising, although the motor was running constantly, and the next day the freezer had the same temperature with the surrounding air.
I called the whirlpool service, a technician arrived the same day and his diagnosis was “beyond repair” as he told me that the parts are so expensive that I’d rather buy a new one blah blah blah.
He charged me for the test 25 EUROS and left.
I was not happy with the testing methods he used and, as the freezer was beyond repair, I decided to make a careful visual check all over.
I opened the internal exchange unit and inspected it. Everything looked new.

Then I started checking the compressor and all pipes that circulate the refrigerant.
All looked ok…exept some stain at the end of the insulated pipe that connects the compressor to the inside unit.

As the pipe was covered with insulation and an aluminum foil I started removing the insulation and the aluminum foil and exposed two pipes, a thick and a very thin one. At some point there was lots of stain all around them so carefully I separated them and examine for anything suspicious.

AHA! About half way up I found it! A small hole to the pipe!

BINGO! That must have been the problem!
Needless to say that I complained to the whirlpool service for their failure to find the cause of the malfunction of the freezer, the same technician came, made a ton of excuses and promised to fix it free of charge.
The freezer was fixed, tested and it works for more than 3 months flawlessly.

CONCLUSION
Do not be afraid of inspect fridge or freezer yourself. As I learned wherever there is a leak there is always an oil stain as there is always some oil that circulates with the refrigerant.