Poor Service/ False Adveri*****t/Still no refund

I purchased an My Bella Mia voucher for permanent eyeliner from Groupon and when I called to make my appointment the lady which I had to try several times and only responded to me by email that there was no the****** available and I must return my voucher. If she knew that why wasn't Groupon aware of it? And why didn't Groupon keep track of their orders and contact the people who purchased this voucher and asked if they would like to be credited or refunded? So I contacted Groupon myself same time, I cant recall how many times and whom I spoken to but each call I made I demanded an email for an reference number and my money to be refunded but when I log onto my Groupon account the money is sitting as credit. I do not want an credit I want my money back into my bank account because I do not wish to purchase from Groupon ever again after this experience! I never believed in online buying this was my first purchase and I trusted Groupon but their service is just pathetic! And customer service needs to speak up more loud and clear and keep up to their promises it's really nerve wrecking trying to get hold of them and talking to them!