I had my flight rebooked last year due to circumstances and Aeromexico gave my family three vouchers.
I am trying to book a flight using the Aeromexico website in incognito window it shows me $2900 for our family. When I call to book this same flight using the vouchers, the price they give me is $4100 and I have around $1300 in vouchers, so the end price ends up being around $2800.
Absolutely ridiculous. The person on the callcenter basically doesn't know why but says he cannot do anything about it as he doesn't have access to the price I am seeing.
Same dates, same flight numbers, same amount of people.
I saw the same issue when I tried to rebook a flight with Aeromexico, the "fees" to rebook were essentially the price of the flight.
Be careful