Back up and running now. The new owner's RSP unfortunately did not follow the correct process. They should have used the Connect & Replace process which would have sent a notification to Spark which they would have then had time to approve or reject..
However in this case, the new owner's RSP ran a transfer and after a few attempts they correctly guessed the name of the current RSP, meaning the transfer to the new owner went through the same day. I have raised this as a training issue with the RSP concerned as the transfer process should only be used when the existing customer is changing RSPs - it should not be used in a move of address/abandonment situation.
And again thank you so much for helping to get this corrected and so quickly!! Spark did seem to be trying to get it fixed but I just don't think they fully understood the situation.
Hopefully when we actually move in two weeks Spark can manage that a bit better (although they did mention that the place we are moving to is already with Spark and that person has their move out date the day before us already as well).