Trust your gut when you begin communicating. Talking to the sales rep should give you an idea of how they handle business. Most techs can attend to any appliances without any issues so if they don’t sound confident it may be worth the time to check somewhere else. It should be easy for a professional technician to repair Ikea appliances. Most of the inner workings are about the same for every appliance regardless of the brand, so talk to your tech about your appliance issues and decide whether or not they are the ones for the job before hiring.
Look for companies that have a good track record. When people hire companies this day and age they leave online reviews to share how their experience went. Take a quick look online and see what others are saying about the companies you are looking into. If someone has found something negative to say it may be worth discussing before paying them your hard earned money.
Try to find companies that are licensed and insured to avoid any issues if anything should happen to go wrong. If someone comes to your home and fixes an appliance only to have that appliance die within a few days it could be well within their contract to replace it if it was because of the work they had done. Insurance would have covered their expenses and helped get you a new appliance where as if you use an uninsured company that cost would fall onto you, and you would have a tough time trying to get anything from that company.