If you use a TA to book, all of your payments would go thru the TA. Thus, you cannot go to the
DCL website and make a payment directly, but can do it with a phone call to a TA or by providing them with the information on their site.
I am not aware of any TA who has a web site directly linked to DCL's. When you "make" an online payment to a TA, you are only providing them with the appropriate info thru their secure site; they will then actually make the payment to DCL.
If you are paid in full, you will still be able to make Palo, excursion, etc. ressies on line. You will be able to see the status of your reservation, etc. just as if you had booked thru DCL.
What you will get in addition by booking with a good TA MAY go well beyond an onboard credit. Sure, if the trip goes well with no glitches, you may not use any services beyond the OBC. But if a flight is delayed, your cruise departure is delayed due to a hurricane, or some other "untoward" event occurs, the TA may have resources that you don't have. The TA may have recommendations for insurance or transportation to port options beyond what DCL offers. When DCL insists that your package didn't include transfers and tries to charge you twice for them, the TA will go to bat for you! A good TA may be worth his/her weight in gold in some situations.
