Twice now I've tried to submit a payment online to "refill" (for the first time) a prepaid SIM. Both times, T-Mobile indicates to me that the transaction was successful, posts a $100.75 pre-authorization to my American Express card, but never actually submits a final charge. The pending charge just stays on my credit card until it expires 8 days later.
The T-Mobile website gave me a "transaction number", but no customer service rep I've talked to has ever indicated that this number means anything or has even acknowledged that any refill attempt has taken place.
T-Mobile really doesn't seem to want my money.