++++ Agriculture - Common organization of the markets - Export refunds - Advance payment - Repayment of amounts unduly paid - Product exported corresponding to that declared but having characteristics justifying a lower rate of refund - Repayment calculated on the basis of the difference between the refund paid in advance and the refund actually due - Determination of the refund actually due - Application of the rate laid down for the calculation in the case of advance payment of refunds (Council Regulation No 565/80, Art. 4(5) and (6); Commission Regulation No 798/80, Art. 2 and 10 Art. (4)(a), (b) and (c))