Bad customer service

I bought I milk shake there and they had a problem with the machine. They pressed hard and it stopped but the cup wasn't full. They then pressed again then it spilled over. I was given it as it was. When I complained then they guy took the napkin he gave me rushly wiped it then tossed it my way and called the following customer without even looking at. I did not receive another napkin. I took a sip as I was walking out, it tasted ice cream mixed with water. I threw that in the bin. Called the store on Monday. The store manager apologized and offer another milk shake. Went again on Saturday for my son's birthday spoke to the manager that was she said that I could lying about the whole. She also wasn't there, the other cashier told her that he is aware of the incident she said I could be lying. I left it no one followed up.