Debonairs has no customer care

I ordered pizza on the 21 December using a voucher. I got the error message that the voucher was invalid. I called the customer care from Debonairs and she affirmed that the fault is on their side, she asked me to email her the error that I'm getting and I did that. She then reassured me that this matter will be resolved within 48 hours.

I have written numerous emails to Debonairs enquiring about this and I haven't had any feedback from them. It's been 9 days now.