Pasted from Wikiopedia:
The Organization for European Economic Cooperation took the leading role in allocating funds, and the ECA arranged for the transfer of the goods. The American supplier was paid in dollars, which were credited against the appropriate European Recovery Program funds. The European recipient, however, was not given the goods as a gift, but had to pay for them (though not necessarily at once, on credit etc.) in local currency, which was then deposited by the government in a counterpart fund. This money, in turn, could be used by the ERP countries for further investment projects.
Most of the participating ERP governments were aware from the beginning that they would never have to return the counterpart fund money to the U.S.; it was eventually absorbed into their national budgets and "disappeared." Originally the total American aid to Germany (in contrast to grants given to other countries in Europe) had to be repaid. But under the London debts agreement of 1953, the repayable amount was reduced to about $1 billion. Aid granted after July 1, 1951 amounted to around $270 million, of which Germany had to repay $16.9 million to the Washington Export-Import Bank. In reality, Germany did not know until 1953 exactly how much money it would have to pay back to the U.S., and insisted that money was given out only in the form of interest-bearing loans — a revolving system ensuring the funds would grow rather than shrink. A lending bank was charged with overseeing the program. European Recovery Program loans were mostly used to support small- and medium-sized businesses. Germany paid the U.S. back in installments (the last check was handed over in June 1971). However, the money was not paid from the ERP fund, but from the central government budget.
In the main no they never paid us back although I think a few nations did like the Netherlands but I'm not sure. So I think we should ask them for the money back with the interested calculated in for say fifty years.