Disgusting customer service received from TFG online support

I am so disappointed at the service I’ve received.

As a regular and paying TFG customer, I am so put off. I was having issues purchasing goods online when I mailed TFG online support, I then received a voucher which when I try to use it, doesn’t work. I then logged another online query with TFG online support, a gentleman called me and tried to help me to see why my voucher wasn’t working, he then advised me that the voucher had already been redeemed by someone which wasn’t me, how do you give someone a voucher that’s already been used?? I am so disgusted by this, and it’s so embarrassing! He then asked me to send him a screen shot of when I received the voucher and I did, I’ve never heard from him after that and this morning I receive a message saying my query has been resolved. Like really!??? How does that work???