Controller's problem then. If the controller doesn't see you doing what he asks he'll certainly get back to you. You'll be protected from any violation because a clearance is not really completed till acknowledged and if your response isn't on the tape, no violation for you.I've flown many times where a transmission for us was blocked and we didn't hear it. Noone repeats the clearance, including the controller. If someone didn't say "blocked", we would have not gotten the clearance. I have no problem with someone saying "blocked". You guys need to get a life....truly.