Log into self-serve. In the Overview tab, just under TOP-UP there is a link for View Transaction History. Check that out for the last 90 days. Does it make sense?
If your plan is not expiring in the next few days, I would wait a day or so before calling customer service. It sometimes takes a day or so for transactions to get posted, especially when using on-line banking and debit cards.
In any event, we have no access to customer accounts here. If there is a SNAFU, you will have to call *611.