Hi, I have posted a return with royalmail, tracking is RY273729484GB. the item is being assessed by the China customs authority for about 2 weeks now. how long are parcel usually held by customs? if there are problems, as duties to be paid, and the seller doesn't take any action, will the parcel be returned to UK? If the item is sent back to UK, am I supposed to pay VAT and duties to receive it back? thanks

I returned an eBay item to the seller through USPS international shipping in August 10, and now it's already September 9. The tracking number is CH074991648US.

2019-08-16 15:44, CHINA, GUANGZHOU, Held in Customs -> Your item is being held in Customs at 3:44 pm on August 16, 2019 in GUANGZHOU, CHINA.

I have read another similar case from the link. It seems not just my only case.
https://www.chinapostaltracking.com/qa/item-at-customs-for-3-weeks-24426/

What really happened in customs in GUANGZHOU? I should get a refund through this return and it makes me annoyed and stressful. What do I do now? There's absolutely no way to contact customs in Guangzhou, and it would be appreciated if you let me know an email address I can reach and let me know how long I should wait more.

Tracking Number: LH144816988US
Your item is being held in Customs at 2:51 pm on July 15, 2021 in GUANGZHOU, CHINA.
Please advise why this package has been held for so long and how do I get it to the final destination?