PATHETIC AIRLINE COMPANY!!!

I've been trying to contact Mango call centre for the past 4 months and I haven't been able to get through to anyone, I'm not sure what's happening with the call centre because it seems like there is no one to answer their calls, I bought flight tickets prior to lockdown I needed to manage my booking as I couldn't travel due to lockdown. How do I get refund or change my booking? I was meant to board the flight on the 22nd of September. I'm not sure what to do now because there is no one I can speak to. This is really ridiculous and time wasting, I've used so much airtime trying to call you and having to wait 45 minutes to an hour is totally nonsense. I need this matter sorted as a matter of urgency, I'll definitely not use Mango ever again.