Greedy and unprofessional

Greedy and unprofessional. We had a blocked sewage line that flows into a septic tank that got blocked. After a call out they took 1 minute and told me that the septic tank is full and left after taking the full amount for unblocking drains. One day later another plumber opened the line and unblocked it without any problems. I called them back to ask for a refund as they could have fixed the problem but did not, the refused to give me any refund not even a partial one. They did not even offer an apology and keeps making excuses.