HardwareHeaven had a (short) interview with Sandro Fabris from Medion, you can read the article over here.
There are a wide range of models on the Medion site; if a consumer doesn't find one which exactly meets their needs can they look to get some tweaks added to an order? For example adding more memory. If not, what is Medions policy on user upgrades, would installing new memory (as an example) void the warranty?
For each model MEDION offers a huge amount of different configurations to meet almost all different customer requirements. Nevertheless if a customer wants to upgrade its Notebook or PC system regarding memory or hard disk capacity this would not void the warranty (with regards to the hard disk or an additional SSD there need to be a dedicated slot available).