air travel – How long can it take for an airline to reply to a EC261 claim?

I think I am entitled to compensation under EC261. I filed an application from Ryanair’s website and, after the automated ZenDesk acknowledgment email, I haven’t heard back for months.

Is the company required to answer within a specific time frame? What is this time frame, and to whom should I escalate if my request is being ignored?

For context, I am a EU citizen living in the UK, and this is referring to a flight between the UK and the EU at a time when the UK was still under EU regulations (before 31 Dec 2020).

(This post isn’t asking whether I’m entitled to compensation – in fact, I haven’t given any details here –, but whether and under what rules I’m entitled to an answer)