I'm satisfied with the work itself, however, the administration seems to be lacking. Appointments are repeatedly rescheduled, then they show up unannounced and get offended when things don't work out. Invoices arrive several months later and are then due immediately – completely unprofessional in my opinion. A shame ☹️

Order accepted, said they would select the items and send a quote. No response! Despite a follow-up call, no further communication. Doesn't keep to agreements. Unreliable. Unprofessional. My advice: go somewhere else if you want to avoid trouble.

A few years ago, Diehl installed a new heating system for us. That went relatively smoothly. Afterwards, we signed a 10-year maintenance contract, valid until the end of the warranty. The secretary told me they would contact me annually to schedule a maintenance appointment. Unfortunately, no one contacted me, and as the year drew to a close, I called the company. They said they had no more appointments available until next year. No apology for forgetting the appointment. This meant we would lose our warranty! Naturally, I couldn't accept that and insisted on an appointment. Eventually, I managed to get one. At the beginning of this year, Diehl terminated the maintenance contract due to staff shortages. I don't think that's legal; a contract is a contract, and the annual maintenance only takes about 30 minutes. They're still accepting new orders, after all. We then found another company and were extremely surprised by the price. Diehl had been charging us exorbitant prices for years! We are glad to have found a different company now, one that is reliable, punctual, and fair. They don't have a staff shortage, so the employees are presumably paid fairly, and yet it's considerably cheaper.