Did someone get online ticket on avainca website? When you are asked to pay, you are asked credit card number, date of expiry, security code and number of istallaments: what are those? I have never been asked number of istallaments before.
The installments (or "cuotas"in Spaish),are common in latinameria. This is because of lower income, but also because of higher devaluation of the currency. It means to pay by installments with very high interest, it is worth it for currencies with high devaluation, but probably not the Euro.
Just put zero installments if you want to pay upfront (probably best for you as an italian earnignn Euros).
thanks, it seems to start with 1, but I guess one installment means I pay all the price at once.