What is EFT's purpose?

In the past 2 years as a ADT client, what amazed me was every time I call a technician to come over and paid them on that day via EFT but still will receive a sms and invoice that says I didn't pay. I'm wondering does anyone work in ADT account department or the person work in ADT don't know how to check their bank statement? (I did the payment exactly the way they wanted from me).