I'm on UltraFlex plan with 250MB data limit every month but I can accumulate data and it doesn't expire. Over time, I had accumulated approx 1.5GB data as of Jul 25, 2018. On Jul 26, 2018, my account was automatically recharged and I lost this accumulated data. I got 250MB data on this date as the new cycle started. Since then I have spoken to the Ultra mobile customer service and written to them. They tell me that I used up that data a day prior to the recharge. I am quite sure that the data was not used because I was home and on wifi pretty much the whole time in this period and I didn't stream videos etc. I sent them a snap shot of my phone's data usage over a month on email in response. It was very little also because I was away for most of the month. My last email to them has gone unanswered for 5 days now. I have not experienced this earlier but had never bothered to check data on any regular basis and definitely not right before recharge. I'm still hoping that they will answer my last email and help me figure this out so that at least in future this doesn't happen!