Is there a fee if a transaction is cancelled or modified?
No. However, a monetary adjustment (debit or credit) will be made to account for the fair market value of the contract. The new deferred contract rate will reflect this adjustment.
In the case of a debit, the new rate will be better than the original rate. In the case of a credit the new rate will be worse than the original rate.
If you have any questions, contact your foreign exchange trader 1-844-990-5655.