Money back

I purchased a few items at Clicks in Cavendish Square on Wednesday 8th April, as I swiped my card the cashiers till screen went blank, I should him the sms on my phone that stated the money had gone off, he advised it will be reversed and that I had to swipe again. I swiped a second time and now had the money go off twice. They told me that within 24 hours the money would reverse back, it's now days later and still nothing, every time I call in they say they will call me back and then never do.