Bad service

Bought a new car l8ft in April and part of the deal was that they would service our other lift. We had to wait 2 weeks for the new lift which was supposed to take 3 days and the excuses was ridiculous. From the other lift they took parts to have fixed and now 4 months down the line we still waiting. He doesnt answer calls but send messages with whatsapp. How unprofessional. We have lost business because of this lift being out if service. He has a different excuse every time and now he wants to bring back the part because couldn't find someone to fix it but the last time he said it was with an engineering company being fixed. I'm still waiting for my certificate for my new lift.