UPDATE: I was able to use EZ Top and it went through - but they charge a big "overhead" to use their service and you don't get the double credit specials. So I'm still determined to figure out how to get it to work on Digicel's website. I've tried again and spoke to my bank again. Bank says they aren't even getting the charge request so they can't unblock something that isn't even coming through as a request.
I e-mailed Digicel (since the phone number doesn't work) and actually just got an e-mail back from them a few minutes ago. I nearly fell over that they responded. I was told the matter was forwarded to the administrators of the Online Top Up service for investigation and that I would hear back in 24 hours. I'm assuming that will be sometime next week because of the holiday. But still, I wasn't expecting for them to respond to my e-mail at all so I am pleasantly surprised!