There no problems porting TCL numbers to VFX, I know several people (including freitasm) who have done this.
The problem is possibly related to the number having already been ported from it's original provider. Was this number ported from Telecom to TCL after "official" portability came into effect last year or was this a port before then?
One way you could do is reconnect the number back with TNZ and later port it out.
I have 2 TNZ numbers, mapped to 2 TCL numbers... and I want both the TNZ numbers be the real and only numbers on our TCL lines... and I have requested TCL to do the same to keep TNZ numbers as primary but TCL is saying they're unable to do it, despite when I moved both numbers over to TCL that they were guaranteed that when true porting becomes available, then I can keep TNZ numbers as primary.