Indeed. I followed the instructions in Clarin, sending a message to the Whatsapp number (+54911 5050-0147) to see if I was really enrolled (i.e., to see whether the enrollment I did on 4 June had been successful). Once you've got the number in Whatsapp in your phone, you just send any message (e.g., "hola") to get started. "Boti", el robot de la Ciudad, writes back and asks you questions. The first answers in order are C (Vacuna Covid), C (¿Estoy en el padron?). Then Boti asks you would type of ID you have. The answer will be A (DNI), B (pasaporte) or C (Otro DNI). Then Boti asks for your document number, and then your sexo (F or M). In my case, he proceeded to inform me that the system had NOT been able to properly enroll me and that I should call 147 (which is a free call, so for those using prepaid don't worry about running out of saldo at the crucial moment).
I called 147. There were a couple of choices to get through to the right area (I think both were option 1). I was on hold for only a few minutes. They passed me through three polite staffers, I had to repeat all my enrollment data to each one (DOB, ID, phone number, email, street address). I got the impression that enrolling with a passport may have been the issue that tripped up the system. In any case, the third person I gave the information to asked me what obra social I have (because some are arranging the vaccinations for their clients, but mine isn't one of those) and then proceeded to re-enroll me, this time properly, I hope. I will report back how quickly they get in touch with me to program the vaccination (assuming they do).
Although frustrating to be in this position, the Whatsapp and 147 calling processes worked well and only took about 20-30 minutes all up.