Airline cancelled my flight from Malta and only offered a voucher

Air passenger rights for flights departing from an EU airport, including Malta, are governed by EU Regulation 261/2004, which gives passengers the right to choose between a full cash refund, re-routing, or a voucher when a flight is cancelled, meaning the airline cannot unilaterally impose a voucher on you if you prefer a refund. Contact the airline in writing, clearly stating you are exercising your right to a cash refund under Regulation 261/2004 rather than accepting the offered voucher, and reference your booking and flight details. Keep copies of the cancellation notice and all correspondence. If the airline continues to refuse a cash refund, you can complain to Transport Malta, which handles enforcement of air passenger rights for flights from Maltese airports, and this can also be pursued through the Consumer Claims Tribunal or the ordinary courts if a satisfactory resolution is not reached.