When you ship Amazon orders you now need to set the Courier to match the exact text for the courier otherwise Amazon will fail to mark the item as shipped.
For Royal Mail, the text must be 'Royal Mail'. For My Hermes you need to set the courier (Details to use for Sale Channels in Shipping tab on the order) as
Other MyHermes
or
Other Evri
and the Service to
Standard Courier collection
This will then set the courier as MyHermes or Evri in Amazon.
You can use this approach to use other couriers not selected by Amazon for example, Fastway. You would set the order courier as
Other Fastway
and the service as what has been selected with Fastway (e.g. Standard)
The allowable main couriers in Amazon can be one of
4PX, Arrow XL, Asendia, BJS, China Post, Chrono Express, Chronopost, City Link, Correos, Deutsche Post, DHL, DHL eCommerce, DPD, DX Freight, Endopack, Fastway, FedEx, Geodis Calberson, GLS, GO!, Hermes Logistik Gruppe, Hongkong Post, India Post, JCEX, La Poste, MRW, Nacex, Panther, Parcelforce, Parcelnet, Post NL, Poste Italiane, Royal Mail, SDA, Seur, SF Express, SFC, Smartmail, Target, TNT, Tourline, Tuffnells, UPS, VIR, WanbExpress, WINIT, XDP, YANWEN, Yodel, Yun Express, Other, Chukou1, CNE, Equick, UBI, Sunyou, Yanwen, Hermes, ROYAL_MAIL, Whistl, Hermes (Corporate), AMAUK, Digital Delivery, The Delivery Group, RMLGB, UKMail, Jersey Post, Caribou, Hermes UK, DPD Local, UK MAIL, APC Overnight, USPS, DHL, DX Express, DX Secure, Parcel Station, AMZL_UK, DX, APC-Overnight, B2C Europe, ITD Global, APC, Parcel Station, Parcelhub, HubEurope, Whistl, Huxloe Logistics, GFS, Spring GDS, Verage Shipping, Digital Delivery, MHI, Truline, Delivery Group, PDC Logistics, Fastway, PARCEL2GO.COM, DEL Deliveries, Parcelink Logistics, Cubyn, Hotpoint Logistics, AMZL, Andere, AO, B2C, CargoLine, Citypost, Delivengo, DPB, EKI Trans, FRACHTPOST, Hellmann, Hlog, honesteye, Huxloe, Interlink, Interno, Intersoft, JPL UPU, Kybotech, Landmark Global, MBE, Mezzi propri, MZZ Briefdienst, NOVEO, OCS Worldwide, ONTIME, Palletline, Palletways, Parcel Hub, Parcel Monkey, Parcel2go, ParcelDenOnline, ParcelOne, PostNL, RBNA, RR Donnelley, Delivengo, Shipmate, Sonstige, Stahlmann and Sachs, Stampit, STG, Transaher, Transaragonés, Translink, Transoflex, Upsilon, DHL Parcel UK, YDH, Bombino Express, Huahan Logisitics, ePost Global, APC POSTAL LOGISTICS, Buylogic, ShipGlobal, JT, COSCO, Flyt, Topyou
You can use the Other {own courier name} to use your own courier name.