If the CM says no, ask that they please immediately escalate to (name
@JGINPL gave you). Explain that this has happened to others and this is the person who resolved this for others. You can also contact that person yourself, but it sounds like DVCMC needs to do some CM training since this looks to be more than an isolated problem.
You might also ask if it would be possible for them to hold the reservation you want in January until your account is set up. If your contact closed weeks ago, you should have been able to book that trip by now.
Good luck and so sorry this is happening. The fact that this broker charges the buyer an adminisration fee is just rubbing salt into a wound.