Company not replacing voucher that they could not redeem due to the store being offline

I was unable to redeem a voucher on 10/2/2024 as the branch was offline. My voucher was to expire the same evening at midnight and I was unable to visit another store. I sent an email ,and the local area rep did call me to apologise and promised to send me a replacement voucher- It is now 14days and I have not received the replacement voucher- I have been following up without success.