From the tracking result, it left China on Jan. 23 but returned back to China on Feb. 12. You'd better contact the sender to let him know this and let him contact China Post to ask why.

Tracking details:

2017-02-12 14:50
Beijing Exchange Bureau, import each other (internal transit)

2017-02-12 08:48
Exchange Bureau in Beijing, has imported opening

2017-01-23 19:17
Guangzhou Terminal, left hand navigation

2017-01-23 18:54
Guangzhou Terminal, arrival

2017-01-19 15:06
Exchange Bureau in Guangzhou, have been exported directly

2017-01-19 13:18
Exchange Bureau in Guangzhou, have been exported to open

2017-01-18 22:48
Foshan philatelic post office letter, left, the next station "South China Sea"

2017-01-18 21:10
Foshan philatelic post office letter, letter

2017-01-18 18:19
Foshan philatelic post office communications, has received send