Peace, what a bunch of idiots! I hate mother don't care nowadays. They've closed the branch in our town, the nearest one is a half hour drive - where the staff don't appear interested, they're never on the till, half the time they don't have the sizes of anything I'm after (me, DD or newborn), which then means a second shlep down the motorway to pick up whatever they've ordered in... I refuse to have it delivered to home because of experiences like yours.
Annoyingly, I get vouchers as a Christmas bonus from work, and one of the only baby shops I can use them in is MC. I hate giving them more money, but I need to buy car seats! And probably a whole load of other stuff that I can't afford to spend real money on at this time of year when I've got Christmas presents to buy.
Anyway. Breathe. 
WRT breastfeeding and drinking, our local BF advisor says that your blood alcohol level is higher than your milk alcohol level, so as long as you're ok to drive, you're ok to feed. Some more info on the Kelly Mom website