Hello, my package is stuck on "Pre-declaration of the item has been received by customs". Is there a problem? LS039216294NL

Hello,
I wonder if you can provide any information on the following parcel: LS040454954NL.
It has been stuck now for 59 days since it was shipped. Last update I am able to see is "Pre-declaration has been received by customs" on 31 March. (This is the second Pre-declaration, the first was on 28 February). No one seems to know anything more about this parcel; I have contacted PostNL about it, but they had no info to give me. Any info would be appreciated.

Tracking Number: EY114589372AU
I am returning an item back to China but it is stuck in customs awaiting for the receiver to pay customs tax. The company (receiver) did not give me a phone number to put on the customs declaration form until after I sent it. It is now stuck in customs and the receiver is claiming that they cannot do anything until they receive a phone notification about it. I have contacted my postal company to try add a phone number to the customs declaration, but they informed me that this was no longer possible from their end. Additionally, they said that it is not mandatory to add a phone number, and that the receiver should have received a letter notice to the address. I also added an email to the customs declaration before posting it. Is it possible that the notice would of been sent to the email address they provided?

How can the receiver contact customs to clear up this issue? I can provide a contact number that the receiver sent after I sent the package as well as any other information that may be required.

Thank you.