Scenario - me at work with thumping headache and no painkillers.
So after work I popped in to the Pharmacy around the corner from my school and ask the Pharmacy assistant for a packet of Solpadiene (after many years of being prescribed all sorts for my hormone headaches these are the ONLY thing that work).
The assistant frowned at me and said "Solpadiene? For you? I think you've bought them from here before!" [stern look]
Me "Probably, I work around the corner so you're very convenient for me"
Her "Well...... I'm sorry but I don't think I'm going to be able to let you have any. I recognise you and I'm sure you've bought them before. We have to make sure people don't get addicted to them, they've got Codeine in them you see?"
Me "Yes I know that, perhaps that's why they work so well?. I have bought them from here before, but I don't see that makes me addicted to them. I only use them when I've got my period. Can I have a pack of 32 please?"
Her "No, sorry. I'm just obeying the law. We can't sell them to people we believe to be addicts!" [you should have seen my face at this point 
Me - "Let me get this right? You are refusing to sell me some painkillers that DO NOT need a prescription, and that can be taken by 12 year olds and that you have on general display? Can I speak to the Pharmacist please?"
Her - "Sorry, she's at lunch for another half an hour".
Me - "Are you going to sell me these headache tablets or do I need to make a formal complaint about you".
Her - "I can't sell them to you when I believe that you have bought them before. I'm trying to help you. I can sell you another product but not one with Codeine in. You can't complain about me because I'm only following the law".
This whole exchange took place in front of 3 other customers. I ended up driving (head thumping madly by this point) 20 minutes across the town to another Pharmacy, where the Pharmacist himself sold me a pack with only the usual warning of "don't take them for more than 3 days in a row and don't take with any other product containing paracetamol".
Should I complain? I am still furious (and I still have a headache).