stole my money, not calling back

Reference number S3-8X027-7FAUE. Brought to their attention on 25 Jan that they had charged me out of bundle rates when my data bundle had not yet run out (and supp**** proof). They ignored my complaint until the 3rd time i queried it, then sent me a cut-and-paste response stating that they'd investigated and that I was liable. I challenged this and was told I would be contacted. The agreed time was 13:30 on Wednesday, they only called at 14:30 when I was unavailable. Was told they would contact me today at 13:30, it is now almost 20:00 and I still have not been contacted. They are trying to dodge me in the hope that I lose interest. You stole my money. I want it back