Medexpress problems

I was supposed to go and fetch my chronic meds from Dischem in Canalwalk just to find out that they didn't have one of my medications in stock in the dosage I require. I've even received the sms to state that my meds is ready for collection. According to the pharmacist at Dischem, they've been waiting 2 DAYS for permission to substitute with a different dosage - just adjusting the number of tablets. So what now?!? I specifically came out all the way to Century City to get my meds today and it's impossible for me to return on another day until next week when I've already run out of tablets. I want this fixed TODAY so that I can go fetch my meds THIS AFTERNOON. DISCOVERY is the one insisting I use their service, so I INSIST that you sort this out IMMEDIATELY!