Dunnes Stores cumstomers are officially ignorant!

I never thought the general public could be so rude until I came across possibly the rudest customer ever. I work at the checkouts in Dunnes Stores and because I'm underage I'm not allowed to sell alcohol I have to sit at a non-alcohol till. On Saturday I was sitting at my till minding my own business and this lady comes up to me with so much alcohol she could sell it to an off licence! There are lots of other tills free but she decides to come to mine. I politely say "excuse me" five times and each time she ignores me until she has all her alcohol on the belt. Only then does she turn round to me and I tell her "sorry i can't serve alcohol at this till". Well she stood there and roared abuse at me. She called me all the names under the sun. Everyone in the shop turned around to look at me and this woman. My hands were shaking and there were tears in my eyes. The names this woman was calling me are not repeatable here but I'm sure you get the gist. And the ironic thing? The manager gave her a free bottle of wine for the "inconvenience". I find this unbelievable because the manager has put this rule in place that I'm not allowed to serve alcohol and I'm supposed to implement it and when I do the manager gives the customer a free bottle of wine..basically Dunnes Stores policy is "If you complain you get a free bottle of wine". I had to leave my till for twenty minutes because i was so shook up but the manager only cared that the customer was satisfied and clearly didn't care about his staff. Crazy.