The calculation is like this
import duty is levied on total price, then VAT is charged on top.
Bike + Postage = £360
Import Duty* (14% for bikes) = £50.40
VAT on total = £82.08
Fedex handling fee (2.5 % min £12) - £12
so additional fees
£50.40 + £82.08 + £12 = £144
so you've come out slightly better than expected.
* this will depend on the tariff code used but 14% the fee for bikes where most of the value/components is of nonEU origin. I'm guessing that either the bianchi frame is built in taiwan or the seller hasn't used the right tariff code , which would reduce the import duty.
Either way its only going to make £30-40 difference to whats owed.