Woolworths complimentary coffee refused - must be HOT

Three weeks ago I ordered an iced coffee from Woolworths using my coffee voucher but I was not allowed to use the free coffee voucher (something I had been doing for the past 2 years). I was informed I could only buy hot coffee. However, when I was persuaded to change my card to a Woolworths Black Credit Card free coffee voucher was mentioned as a benefit (hot/cold was not specified). Woolworths website reads: "Get a free coffee or tea at any Woolworths Cafe, To Go or Tapas Bar, twice a month." I had to leave the coffee behind. I wrote to Woolworths and no response in 2 weeks. I'm about to call again. This may seem a small and insignificant matter but it makes no sense to me that the complimentary coffee can only be "hot" when the iced coffee is even cheaper. How at the end of the day does this make a world of a difference to Woolworths when it makes a big difference to me since hot coffee makes me nauseas but I enjoy cold coffee?