Repay a client from your balance

Applies funds from your own settlement balance to the client's outstanding receivables. Use it when incoming funds could not be attributed to a client automatically and were credited to your settlement account as unallocated. The funds must already be on your settlement account for currency and paymentRails (see GET /accounts in the Account API); an amount above that balance is rejected. Allocation is FIFO across the client's active receivables; the request does not select a particular receivable. Any amount beyond the client's totalRepaymentAmount remains on the client's settlement balance. The response acknowledges the request; read the receivable and credit account after settlement.