Update: My experience with SBB regarding my lost property.
As mentioned above, I went for a day trip to Zurich and ended up losing my bag on one of the trains. The bag had my passport, my dorm keys, my debit cards, my student ID, and my health insurance card. Basically, that bag had my everything. I had to come back because I am a student and I did not have the money to stay in Switzerland however I had registered a complaint with the SBB lost & found office. I was told that the services were extremely good and there was a solid 90% chance that my bag would be found. Now I can say that I can’t agree more.
Within just 2 working days, I received an email saying that my lost property had been found, and in the next 2 days, I was asked to pick up my bag at my chosen station which was Konstanz. The train station timings were given. I went there and showed the email as well as my ID and got my bag back. They charged a fee of 20 CHF. My bag had everything that I had kept in it. So, to summarize, within a span of 4 working days, they were able to locate my bag and hand it over to me.
Some notes:
If you are asked to take the bag from a chosen train station, remember that it will be in the train station and not anywhere else. Find an office that is located in the train station and check the timings given online.
If like me, you have asked SBB to send your bag from a city in Switzerland to Germany (Konstanz), remember to look for the lost and found faculty of SBB and not DB as there are many lost and found offices of DB as well and you might end up getting confused.
Lastly, just remain calm. Mistakes happen but just remember to be patient. SBB has an excellent service for lost and found and in most cases, they find your property and ensure that it reaches you safely.
I hope this can help others who are in a similar situation.
Thanking You
Sanjhi Sardana