A/C Malfunction

[PacificBlue]

2009 XF 3ltr diesel: Initially the A/C stopped cooling - Condenser/receiver dryer leaking therefore changed April 2015. A problem still persisted in that the A/C would not stay cold, the external Ambient Temperature sensor was then changed, to no avail. The Low side valve/pipe was then found to be leaking. Pipe changed but again a problem still existed whereby if the cabin was initially hot it would take up to 20 mins to start blowing cold air and if subsequently the car stopped or crawled ie. a traffic jam, the A/C would blow ambient temperature air. After reading a bulletin from JLR (Unsatisfactory A/C function) the DPV in the compressor was changed. Did not fix. As a last resort the 'In Car Temperature Sensor' was changed. The fault still exists and we have run out of ideas. Any help with this would really be appreciated!!