It also broke rules limiting the nusiance calls to two in any 24-hour period, more than 36,000 times.
Homeserve said it would send £10 in compensation to each wronged customer, and blamed the issue on an outsourcing company that it has since axed. It added that it has stopped using the technology that supposedly detects answering machines and hangs up.
Last year's mis-selling scandal forced Homeserve to suspend one of its call centres and axe 200 jobs, and prompted an investigation by the FSA.
Shares in Homeserve, which have nearly halved over the past year, on Thursday fell 2.7 to close at 234.7p.