Hi pn,
Goods received through post has different thresholds, you will not have to pay anything to the delivery company to receive goods worth less than £135 unless they’re gifts over £39 or excise goods (for example, alcohol and tobacco).
More information on this on below link:
Tax and customs for goods sent from abroad
You can get a relief if you’re re-importing goods into the UK that have previously been exported or transported from the UK. This is known as Returned Goods Relief. But this can only be done at the time when goods are sent from abroad and customs declaration has been filled by the postal company.
Customer can now look in to a reclaim on the charges by filling BOR286. You need to complete this form for parcels or packets received through Parcelforce or Royal Mail only, if you believe that Customs Duty or import VAT has been incorrectly calculated on your imported item.
Report incorrect Customs Duty or VAT on items imported by post (BOR286)
Thank you.