Responsa על בבא קמא 222:6

Q. A sent a pledge to B through a Gentile as security for a loan to be contracted through the Gentile. Upon A's seeking to redeem the pledge, B refused to accept the money, claiming that the Gentile had sold him the pledge.
A. The Gentile had no right to sell A's pledge; consequently, A has a right to redeem it.
SOURCES: Pr. 728.