Curtis Total Service review: They asked to pay in advance, but I wasn't sure that it was safe

I used the services of the company Curtis Total Service couple of times. Two times their services were great, but the last time when I contacted them and told that I searched for the plumber, they started to ask for payment in advance and shocked me that the plumber was so busy and they couldn’t tell me the price time of his arrival. I wasn’t happy with such replies and that they wanted money in advance. Did someone pay them in advance? Did they scam you?