Doesn't the invoice have the username on it?
Anyway, why not just ring Jason or Enta support from the line in question, as they'll be able to see the line number on caller display. Then it's easy for them to trace, once you answer whatever security questions they dream up.
My broadband basic info/help site - www.robertos.me.uk
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"Where talent is a dwarf, self-esteem is a giant."
- Jean-Antoine Petit-Senn.
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