Not clear on expiry date and bad attitude

I very excitedly had my first online buying experience with Zando two weeks ago. It all went very well, I got my goods and was very happy. I received a voucher from them to use on my next transaction. The voucher is valid for 14 days. I incorrectly assumed that the voucher was expiring today (Monday 13 July) as I had been given on Monday 28 June.<br> <br> When I called the call center to inquire I was told that the voucher had in fact expired yesterday. I made the suggestion to rather put an expiry date on the voucher instead of stating that it is expiring in 14 days as this can be open to interpretation. The call center agent told me that this was NOT HER fault. I then had to say I am not blaming her but am simply making a suggestion as a customer.<br> <br> So in the end I can't use my voucher due to a miscalculation on my part, have spoken to a very rude person on the phone and now don't actually ever want to use Zando again, after my very exciting first experience.<br> <br> I am very disappointed to say the least.