Tribunal Cancelled

Just had a phone call from the Court to adjourn my Tribunal for PIP (reassessments) appeal. Totally shocked - waited over a year for my hearing and now the tribunal have decided they need to seek further medical evidence. Can they do this at this late stage ? After all the correspondence back and forth where I have repeatedly complained about the HP and decision makers not seeking FME. I feel totally deflated .... 65 yrs old with a degenerative spinal condition ....finally thought it was all going to be over and now this. The Tribunal service is now sending me a letter seeking my permission to allow them to contact my doctor. Another 3 or 4 months of waiting anxiously ...... Is this allowed? Any advice plse.