Zando not replying, after a fortnight, to a new potential customer, regarding an online voucher not working

I have been trying for at least two weeks now to get a reply from Zando. I recently created an account and was sent a first time buyer voucher. However, the voucher is not working when I attempt to check-out items I wish to purchase, and emailing and phoning Zando to try and get through to them is impossible. Their customer support hasn't rep**** to my emails for more than two weeks.

I understand that the lockdown is putting strain in everyone's ability to work productively, but surely this is the perfect time for an online retailer to capitalise, given the spike in online purchases, and up their service offering and customer support?

The only reason I haven't given Zando 1 star is because I was sent the generous voucher in the first place. Said voucher, as I mentioned however, is spitting back an error during check-out!