I bought a SIM card from the Viettel counter at the arrival hall (third from the left after heading downwards from the immigration counter).
The staff at the shop told me it would give me unlimited data for 5 days and cost 290,000 VND. I paid and asked for a receipt, but was told that they do not give receipts and merely record purchases in a log book.
The SIM card ran out of data after only 2 days. And I subsequently noticed that the face value of the card is only 90,000 VND.
Could anyone advise me on what to do in this situation?