We had our septic tank cleaned because of sewage overflow in our basement. After it was cleaned there was still overflow. The septic tank guy said the sewage was not reaching the tank. We then ran a snake frthrough the clean out pipe and through one of the toilets. This cleared it, but now a week later the overflow is back. Ideas?

Means the blockage is back. In snaking you probably went through a soft blockage which has now closed up again Snake again with power snake.