[lxgr]

Banks can (and often do) outsource chargebacks to their processor or another third party, but never the card network (since that’ll be the entity ruling on the case in the very unlikely case it goes into arbitration).

Viseca seems like it might actually be an issuer directly (it’s also a common model that banks only act as program managers, delegating actual issuance to a different entity) but I’m not familiar with them.