It's very easy to order and adjust your prints by downloading the Saal Digital software on their website. You can also order online if you have less time. As I already mentioned, we used the french interface, so your interface might not looking similar depending on your language/country choice or eventual updates:

We chose the option tableau photo "Alu-Dibond" (Wall Decors - Alu Dibond in English). As you see many other options are possible:

Now you can modify different options: the format, mounting/frame and item orientation.
We decided to order a print of  50x75 including an aluminium subframe (no additional charges) and the orientation "Portrait". Note, that you can't change the orientation at a later moment. I had to start over again, because I missed this option in the first place:

After this, it's easy to upload your picture from your computer. You can also move it from a folder to the interface. Something missing here, might be an option to add also pictures from other apps or clouds like "Dropbox". Maybe they added this feature in the meanwhile. 
You can now adjust and align your picture:

The final steps are to check a last time if the picture looks how you want it to be. At this point you can still change to a different mounting or frame:

The shipping was very quick in less than a week. I got the packet from DHL and the product was well protected.

I have to admit, that I am very satisfied with the print. 
The sharpness, the colors and crop look very close to the original image on my calibrated screen - judged by my eyes. There might miss some saturation, especially for yellow and some overall luminosity, but I might have could change this in advance in the software. 

Anyway, by comparing with other print companies, I prefer the look and quality of Saal Digital

Below the comparison of the original image and the photographed print on Alu Dibond:

Saal Digital Fotoservice GmbH is a German Company, that's why they might still be less known in the UK and France.
But many people don't know, that this company is a partner of many huge print and photography companies and brands in Europe. 
Their statement:
"We are a professional photo lab with great enthusiasm for photography. We are striving for further development of our products in order to achieve higher standards and to meet the needs of our customers. As a modern online service provider, we are specialized in high-quality photo products, including photobooks, photo prints, posters, calendars, greeting cards, wall decors (Alu-Dibond, acrylic glass, PVC foamboard, GalleryPrint), as well as photo gifts."

photo by Marco Mazzini Photography
Makeup by Lynn Schockmel Body Art Luxembourg
Styling and Design by Fernando Nogueira Design
models: Jessica Estrela, Hugo Conde de Carvalho, Eli Ondoa & Katia Dos Santos
Location: Gino's
You can buy the full issue in print or digital here

photo shoot by Marco Mazzini Fashion photographer
Model: Lina represented by Modinlux Agence de Mannequins | Julie Modinlux
Styliste/Designer: Kathleen Guérisse | Créations du Général Guérisse
Makeup Artist/Hairstylist: Lynn Schockmel Body Art Luxembourg