Field descriptions:
mandateId: The identifier for the mandate used for this collection.
mandateReferenceNumber: The bank reference number for the mandate used for this collection. This should only be specified if this mandate has already been authorised by the bank and creditor/client.
collectionDate: The date on which to action this collection.
trackingPeriod: The number of days to track this debicheck collection (max 10). This field can only be set if traking is enabled on the mandate.
amountCents: The amount (cents) to collect.
debitSequence: The debit sequence for this collection. Use FRST if this is a explicit "first" collection for this mandate, otherwise this value should match the debit sequence on the mandate.
Accepted values: FRST, OOFF, RCUR.
externalReference: A unique reference, which can later be queried for this collection. If this value is not unique you will get a HTTP 400 response ("Collection with this external reference already exists")