I've never really had a problem with ali except once when i was being charged 2k customs for a Rs. 800 item. I refused the parcel and contacted the local post office later to know who which office applied that absurd duty so I could haggle with them. I did not get any useful response and so this is now my rule list for ordering:

- be prepared to lose the item. it's a risk. Otherwise go down the official route and pay whatever duty the customs dept deems is correct. forget the slabs/rates etc. the haggling is not worth it.
- break shipment into 500g units if possible. talk to the seller, some of them oblige.
- do not order high valued items. ask someone to carry it for you if possible.