in out country Tanzania they charge us alots money if the track numbers didn't start and ended up with letters, so can you please help us save the cost and add letters beginning and ending of the track number of all orders please!?

Hello, I'm a particular and I usually like to send letters and small things, never more that 2kg to my different friends all over the world, I have been using the normal tracked letters and packages of the post office but it has already happened more than once that they write something wrong or they suddenly tell me it's way more expensive than it should for the weight and size, is there a way I can personally register the letters/small packages as a particular online and idk print a label? Or is there any other type of shipping for small parcels that I can use to send things to my friends?

Friends and family members have sent us the last month letters from Germany. They are sent off in November/ December 2020 and January 2021. Until now nothing is arrived in Beijing. This are normal letters, without a tracking code. Why hasn't a single letter arrived so far? The postoffice said I have to wait. But how long? And who can help me?