Pay your electric bill over the phone
The easiest and fastest way that I know about is to call the phone number on the back of your Edesur bill. (809-563-1844) They are open 24 hours a day, 7 days a week.
They ask for the contract number. (It's in Bold and labeled NIC on the front right side of your bill beside your name).
Then, they will confirm the amount on the bill.
Then, they will ask for your credit card number and expiry date. (Mastercard or Visa).
Finally, they will give you a confirmation number that the bill is paid.
Usually this all takes about 2 minutes. I pay my bill this way every month and it has never been a problem.
For me, it is far better than driving to some Edesur office or bank and waiting in a long line. (The only bank that lets you pay your Edesur bill is Ban Reservas).