Disgusting service from Simply Asia, Howard Centre

I have been buying from Simply Asia at least once every week for years. I have always bought the sushi half price special as take-away and this particular day I came to collect my sushi at Simply Asia in Howard Centre and I get the bill for full price. I ask about it and the manager simply says, I need to pay full price. After all this time I have paid the sushi half price deal from Tuesday to Sunday and taken it as take-away at all the other Simply Asia restaurants and suddenly at this one I wasn't even informed beforehand that I would have to pay full price. It was so disappointment that they weren't even willing to assist in any way but the manager just shrugged me off. He even went as far as taking my number and email and said he would let me know what came from this query and to this day has obviously not gotten back to me. That was my last buy at Simply Asia.