I have been trying to enquire about a voucher and have sent three separate emails over a period of time, yet I have received absolutely no response

I have been trying to enquire about a voucher and have sent three separate emails over a period of time, yet I have received absolutely no response. There is no alternative contact number available, no follow-up, and no way to speak to an actual person. The lack of communication is unprofessional and very disappointing. Based on this experience, I would not recommend them.