Frost building up inside refrigerator

Please make sure to click on General above and select the correct appliance type first.

Brand:Samsung
Model Number: RT46K6631SL/ED
Main Symptom: Frost building up inside refrigerator coils, and then turning to ice
What happens & when: First, I am from the USA, but moved to Ecuador 10 years ago. I live in Ecuador and purchased the refrigerator here. The frost builds up within 3-4 days. I’ve been using a hair dryer to melt it. I’ve had 2 technicians come out to look at it. The first one, which is supposed to be a Samsung specialist, Asitec, told me they needed to replace the back covers for both the freezer, and the refrigerator. I don’t understand this, because nothing is wrong with them. They also said they needed to replace the gasket around the freezer. Again, nothing is wrong with this. I will say, however, when you open the freezer then close it, it is impossible to re-open. You must wait at least 5 minutes. Also, they said the temperature sensor (DA32-00066B) that is connected to the coils in the refrigerator needs to be replaced. What confuses me is these technicians never used a multimeter to test anything. I’ve attached an invoice from Aasitec of what it would cost for them to fix the refrigerator. A few caveats. They told me it would take 25-30 days to receive the gasket, because it needs to be imported. As such, I would have to wait that amount of time for them to come out and fix the refrigerator. Also, they told me their warranty is 3 months. I then had another technician, not a Samsung tech. but someone who works on refrigerators look at the appliance. He came with his multimeter, and tested everything, including the freezer and refrigerator panels. He told me the only part that needs to be replaced is the temperature sensor. However, he was unable to get the part here. As such I’m contacting you to find out if you have this temperature sensor. I have people who are in the USA now, and will be returning to Ecuador in a week. My thought is if it is only the sensor I could purchase it from you, and install it myself.I’ve attached a photo of the ice buildup in the refrigerator, as well as the model number, and the quote from the company Aasitec. Any assistance you could provide me would be appreciated. Thank you:)

Error Code (if any):
Parts or tests already tried: used mulitmeter on the panel in the freezer, and refrigerator. They were fine. Technician used multimeter on the back of the refrigerator and said everything was fine. Technician used multimeter on Temperature Sensor in refrigerator and said it needed to be replaced.
Photos / video link: https://drive.google.com/file/d/1hvXehUmJ04_bY4wHLpiDneCs-nbPV4AW/view?usp=sharing

From the picture and description, the issue sounds like a defrost issue. The heater, control, or sensor would need to be tested with a multimeter to determine if they are good or bad. However your exact model does not show up in our resources, and you will likely need to contact the manufacturer for help with the correct parts and part numbers for your model.