Mail declarations? (Guangzhou)

We are having some kind of issues getting packages received here in GZ. We have had FOUR other packages come straight through with no problems, now all of a sudden, the government is telling us we have to come make a declaration on the packages and then pay taxes on them?!?! Does anyone know what causes this to happen? I am having a VERY frustrating time in GZ and this is NOT making me want to stay any longer. I have NEVER had so much problems sending money or receiving packages. Is there something I can do/tell the senders to do to/with the packages to avoid this from happening again? PLEASE HELP ME!!! *pulling out my hair*