curl --request GET \
  --url https://api.opereit.com/v1/contracts/{contract_id}/surcharges \
  --header 'Authorization: Basic <encoded-value>'

{
  "data": [
    {
      "id": "<string>",
      "contract_id": "<string>",
      "slug": "fuel",
      "display_name": "Fuel surcharge",
      "value": "15.00",
      "currency": "EUR",
      "is_waived": true,
      "origin_country": "<string>",
      "destination_country": "<string>",
      "service_type": "<string>",
      "calculation_base": [
        "<string>"
      ]
    }
  ],
  "pagination": {
    "cursor": "<string>",
    "has_more": true
  }
}