My "require" comments were tongue-in-cheek.
In the air (when under pressure to finish the navex) Perhaps a "request advice on any available alternative to traverse CTA due training requirement destination YXYZ" might also help rather than just a simple request.
If advice/clearance still not available then "pretty please with cherries on top" is your only possible reply.
The original poster clearly needs to open alternative lines of communication - both with ATC (via phone) and instructor/CFI if he cannot find a way of clearance in the air.
OP please report back and let us know how you get on.