Yes you can adjust them, just as you would with any headlight using the white adjustment screws on the back of the headlight, you don’t need anything special just to raise them a little! and no diagnostic settings or self levelling will be altered so don’t worry about that, when the dealer states ‘within spec’ what they mean is it is in the range that will anable an MOT pass, all you need to do is bring them up to the highest level within that range, it will quite literally be like night and day once you’ve done it, either do it yourself by raising an equal number of turns on each side (between 1/2 a turn and 3 turns will be all that is need), be careful if you’re not familiar with the procedure as it can be quite easy to ‘get lost’ and completely put them out of spec by turning the left/right screw instead of up/down and then losing where you were!, if you’re not sure take it to a place that does MOT’s and ask them to set them to the highest permissible level using a beam setter.