Dissatisfied customer

My husband called Plumbers on call to unblock a drain. They completed the job on the 8th July 2015 and we paid R750 cash. Not even two weeks later, the drain was blocked again. He called Plumbers on call who came to fix the job. The workers said to my husband that something was blocked or broken and that they cannot unblock it. Jarred told them to carry on with the rods. They managed to unblock it. Jarreds lady phoned and said they think they need to put a camera down to see if anything is broken underneath the house. She quoted R1500 and my husband told her NOT to go ahead with this inspection as wanted to discuss this with me. The job was sorted anyway and we have had no further problems since this was done on Monday the 20 July. On Tuesday 21st I received another account for R1500!!! How does a company charge again in less than two weeks after the first call out? AND a 3rd account was emailed on the 21st!!