Clicks puts in no effort to look at vouchers

We received a R200 voucher to use at Clicks from FNB ebucks. We can use the voucher if you spend R800. We purchased items of R1000 and when wanted to use the voucher at the Clicks at Mall@Reds, the cashier told us that they dont know how the vouchers work. We called the manager and the excuse she came up with was that the system was down. We then left the items, went to Dischem and used our Dischem voucher there without any issues. I cant believe Clicks did not put in effort to see how the voucher works. Very dissapointed in Clicks in mall@reds.