We recently bought a home built in 1960. We were having issues flushing the first floor toilet and found that the waste line was almost completely blocked with calcium deposits. Our plumber tried to dissolve it with acid but he couldn't get down deep enough. We are on septic, so I didn't push for using any more chemicals. The waste line is 4 inch cast iron and totally exposed for access in the basement ceiling. There is about 4 feet of line that he is proposing to replace with PVC. It has two bends in it and connects to 3 other smaller lines before it goes to the brand new PVC piping for the septic system. Originally, the plumber said about $300 to replace but they just called and said that now the cost is $750 because he has to cut and reconnect the other pipe connections. Does this sound reasonable? Thanks for your input!