Technically OK but otherwise unreliable, untrustworthy, unresponsive

Ernest and his mechanics worked on my Hyundai ATOS for several weeks. Initially I was satisfied with their work as well as responses to e-mails and phone calls. However, about three weeks ago Ernest started to refuse to pick up his cellphone or answer e-mails. He began making promises to come to my house at certain times but simply did not show up. He knew that besides the ATOS I have no other transport and cannot even buy food, Yet when asking to tell me when he will come to my house, he refused to answer phone calls or e-mails. He has not finished the last job of acquiring and installing an alternator and making it work in the ATOS. Although I already paid him R3220 for this job, he still needs to inspect the alternator connections, remove the alternator if defective, take it back to the store and exchange it, and reinstall it. I don't know why he changed his attitude and has become totally untrustworthy. CAN ANYTHING BE DONE? Yet he is completely unresponsive and unavailable,