I'm not sure I understand the question/problem?
Are you saying that once up to temperature with the heat setting at MAX the climate control still blows cold with the air con on? So, if you switch it off it's warm?
Gone but not forgotten:
325i M Sport (E92), Black Sapphire, Coral Red Dakota, 19" 225's, Seat Heating, 6FL and de-badge
Replaced by 6.2 litres of AMG powered C class.