fixed term pip award made by tribunal ending

i seen someone from cpag tweet re this earlier today and then i get a case.

client awarded pip on appeal for a fixed term. pip renewal form sent in jan of this year. no decision yet and pip expired. DWP saying they cant do anything to extend the tribunal award and i think that may be correct (please point out im wrong here if possible).

is there any way around this other then the DWP as a solution making the shortest pip award possible and then re-assess when thats due to come to an end?

sorry - just seen this thread which is the same issue https://www.rightsnet.org.uk/forums/viewthread/15981/