My husband and I both purchased 150,000 miles using the 100% promotion for a total of $2,250 each. My intent was to book an award flight for my sister-in-law and brother-in-law from Sydney to Paris on Thai in business class for 87,500 miles plus $98 in taxes and fees. I was then going to book the return from Venice to Sydney using the 62,500 remaining miles plus about $558. I booked one ticket on my account with no issue and my husband also booked the flight from his account, but after completing the tax payment page, the website returned an error message regarding the payment, but gave us a record locator and a telephone number to call. We were able to book the return flights without issue. Then the fun began. I called the number provided and tried to pay the tax, but was told that they could see the reservation but could not take the payment. I was told that someone from another department would have to call me back to take the payment. This was after being on hold for over 35 minutes and transferred from one department to another. I was concerned, but decided to see if someone would call. I asked how long the reservation would hold and was told 72 hours. The next day passed without a call, so I called again with the same wait times and similar results being told that they would have to call me back to take the payment. The agents I spoke with were not authorized to take payments over the phone. Another 15 hours passed, and I called again. Same result. After nearly 48 hours and several hours spent on hold, I finally got an agent named Carlos who was able to help me. He told me to sign on to my frequent flyer account and create a PIN that could be used for telephone payments. I did then, and he prompted me to enter the PIN and the computer then requested my payment. The call then returned to Carlos who completed the transaction, which incidentally, cost an additional $50. This was quite an ordeal, and I'm not sure I would like to repeat it. 2 business class tickets on Thai Airlines from Australia to Europe for less than $6,000 was quite a deal, but the anxiety was also very real. Beware of the Avianca website.