Without being sarcastic and hopefully not being rude either (quite rare for me) we give you what we can when we can, just to stop you calling 'levelling FL***' or 'approaching FL*** looking for higher'. We do have Mode C readouts and are fully aware of this. A solution is to slow down the rate of climb so we call out the next level before you need it. If its not too busy, even ask for the climb rate of the other a/c. You may not get an answer, but sometimes I try to help, even if its just an a/c type, expecting you to understand the poor performance we are getting. I dont do DAV so am only guessing, but I would say you are stuck under either MAN slow climbers, or East Mids, seem to be many at the mo not performing great.