Hi, I was using a matrix sim card in Tokyo and mainly the purpose was data only. Voice was minimal. In the middle of my trip my data had become really slow so I had to call the customer center to understand the reason. I was told that it was from the back end and would be corrected which actually happened. But when my bill came, it was charged for data usage. While in my plan I had taken an extra of 1GB data over an above the 1Gb already in my plan. When I called the support team, they looked into the issue and then re-sent me an edited copy of the e-bill. I really appreciate their honesty  and giving the time in hearing the issues out. With my past experience with other users, it was never the case.