You can try contacting USPS on their American “toll-free” (freephone) number +1 800 275 8777. However some doubt if you’ll be able to obtain customer support from the UK on this phone number and you will have to pay a charge if calling from Britain as it is not a UK freephone helpline.
Couriers Contacts
FedEx Contact Number: 03456 07 08 09
Contact FedEx by calling their UK customer service telephone number 03456 07 08 09 for parcel tracking and general enquiries about their delivery & pick-up locations.
Hermes Contact Number: 0330 333 6556
Contact Hermes customer service advisors by calling their general enquiries UK phone number 0330 333 6556.