Ackerman's-could your staf be any ruder?

I went into Ackermans in Hillbrow on the 16 April, and purchased a cellphone. Initially, when I was puchasing the phone, the salesman was extremely helpful. He set my phone up for me and was very pleasant. This however changed once I had made the purchase.I have been back to the store for help with the phone a few times since I made the purchase. Each time that I have gone back, he has helped me, but with an attitude. Each time he has said that he wouldn't help me again, and has said that he is too busy. He sometimes lacks the kwowledge to help me I find this salesman's attitude and knowledge lacking, and I certainly won't be doing any more purchases at any of your branches if this is the treatment that I get.