What is the Sharia ruling concerning who is responsible for paying the remaining amount of the goods' price, is it the businesswoman who received the goods in her office or the businessman who bought the goods from her?

The remainder of the money due to you for the clothes is a debt owed by the merchant, and she must pay it. Two scenarios are possible:

The first is that your receipt of a portion of the money was as an agent for the merchant to the other merchant, for the purpose of settling a part of her debts. In this case, the merchant must pay the remainder.

The second is that the merchant transferred the debt to the other merchant (i.e., performed a hawala). If you accepted this transfer, your right to the debt shifted to the other merchant, and you cannot demand the remainder from her. If the other merchant delays payment or becomes insolvent after the hawala was valid and you consented, then according to the Shafi'i and Hanbali schools, the assignee (the muhal) cannot return to the assignor (the muhil). As for the Hanafis, they have a detailed explanation.

It is advised that the merchant hasten in paying the money if the transfer (hawala) was not completed.