Reliable Car Service in Berlin

Check booking.com to see if it offers such service.

I used Uber while in Germany without problems but YMMV.

Why not use a regular taxi?

I agree. Just call a taxi or if at a hotel, have the front desk call one.

I have used Blacklane multiple times in the past in Berlin (and other places). I have always been pleased with their service, but they have become quite pricey.

https://www.blacklane.com/en/

I have been in Berlin countless times and on every occasion when I've had an early departure the reserved taxi has NEVER failed to show . you don't need a private car service.

Furthermore, there are a plethora of taxi stands throughout Berlin, invariably one near where you will be staying, that can be used as a fall back.

Thanks all for the replies. I seem to have more bad luck than good with taxis, from drivers arguing who will get the fare, to hotel personnel flagging down a taxi which then drove off after being told the airport was the destination, to a driver banging on his meter 5 minutes into a 40 minute ride saying it did not work. I made him pull over and we agreed on a fare before continuing. Having said all of that I will try a taxi. I'm just concerned with my little German and communicating with the driver. I will take Rick Steve's advice and have my airline and terminal written down to hand to them, and as the concierge said, make sure the meter is turned on.

a taxi which then drove off after being told the airport was the destination

In Germany, a taxi is a normal means of public transport and has a transport obligation within the city and to the airport. In addition, the airport transfer is a lucrative trip, no one would say no anyway.

I'm just concerned with my little German and communicating with the driver.

You probably will have something in common with the driver. Often they speak a little English rather than German. The best thing is, you speak Afghan ;)