We are very sorry that you had to pay more than expected for your order.
There could be several reasons.
We provide payment in the currency that you selected during the ordering process. If your local currency - not the one you have chosen, then your bank will make the conversion of their course.
When you next time we'll make the purchase, click on the check box in the upper right corner of any page, select the window "Change Currency" and then click on the desired. Then all our prices are quoted in the currency of your choice, and payment will be made is also in it, if you change it to complete your order.
If you use a promo code, discount may not apply to all items in your cart. Some promotional codes are exceptions, which you can see in the conditions of use of each to send you promotional code.
If you still think that you have to pay less, please contact our customer support, and we will try to help you.