Invoiced for a workshop I did not attend

NeDICC organised a workshop for the 1 August at CSIR (Machine Actionable Data Management ), and this was communicated via email. The workshop fee was R100 and there was a link which could be used to RSVP if one was interested in attending. I duly completed the link to RSVP. Unfortunately the R100 indicated as the workshop fee was incorrect and a subsequent email was sent to correct this to R1000- recipients were informed that the initial email must be ignored, a new email with the correct figure (R1000) had an RSVP link. I did not reRSVP as I had initially RSVP'ed based on the R100. Confirmation of attendance was 'supposedly' going to be dependent on payment (which to me meant that it I had to pay first so that my attendance can be confirmed), Apparently my name name was on the list of attendees even though I did not reRSVP (after the fee correction) or pay or confirm my attendance? It is interesting that the Cancellation of the error-email (R100) was ONLY applicable to the email and not the RSVP link which was part of the email?? If the error email was supposed to be ignored, why were the RSVP's that were made based on the error email not ignored or deemed invalid? In short, the RSVP was valid but the email had to be ignored! This is very disappointing as it was NEDICC's mishap that led to this miscommunication.