While I have limited interactions with LOT (I buy through our Corporate Agent who also handles these cases), during COVID I used once or twice Facebook Messenger and it was fairly effective.
I would do this:
1. Find an available flight I would like to use to get to/from WAW
2. Send them a message asking to involuntary reissue quoting EU261 Article 8:
(b) re-routing, under comparable transport conditions, to their final destination at the earliest opportunity;
This way you will have everything on paper and - in the case they refuse - report the case to Swedish EU261 enforcement body which is Konsumentverket.