There should be no issue with increasing the wheel size but you will want to try and get a lower tyre profile that matches the original wheels' overall diameter. If the overall diameter increases you are effectively 'gearing up' the car, which will decrease performance, increase fuel consumption and likely give you an incorrect speedo reading.

To save time finding the right fitment of aftermarket wheel why not have a look at online auction sites to see if the AMG upgrade wheels for the B-Class are available used? Any good bodyshop will be able to powder coat the wheels to make them black.