There's certainly a procedure for helping in situations like this one. I was downgraded due to a cancellation at LHR T3 and was only Bronze at the time. It was back in early summer when security queues were insane, especially in T3. I was about to ask, but unprompted the agent issued me a boarding pass with 'FAST TRACK AND LOUNGE ACCESS' printed on it. Saved me about two hours at least.