Reward flight change

My parents are due to fly to Istanbul on Thursday for a week using a companion voucher. They’re both feeling extremely apprehensive about going amidst all the conflict in the Middle East. My mum tried to call customer services but couldn’t get through, I’m sure they are inundated at the moment with calls. She will try again tomorrow but I wanted to ask if anyone knows whether it’s possible for them to change their flight to another destination using their avios and companion voucher? I imagine this is tricky as turkey is still deemed safe to fly to. Thanks for any help or insight