Malev offer upgrades on https://www.optiontown.com/
Costs between £30-60 each way normally. You pay an additional £3 registration fee. Upgrade does not clear until a few hours before the flight. If it clears you should then get full miles and TPs. If it doesn't clear you get the upgrade cost back less the registration fee. I'm trying this out on a WAW-BUD flight on Tuesday so will report back if it works!