PIP Extension

Hi, I am not sure whether I will have completed my PIP Review form by the end of my extension., I have already been allowed 4 weeks extension,, but have nightmare personal circumstances at he moment. My question is please, if I do manage to get another extension , my worry is that my Review assessment by DWP etc may not have been competed prior to my existing Award running out. If the DWP etc assessors were to take several months assessing my Review form, and my current award expired meantime - what would happen? I assume my PIP payments would stop, from between the expiry date of my current award until the Review assessment completion date. (Then resume from the completion date of the Review assessment assuming awarded PIP again). But during the period when current Award expired and Review assessment still being processed by DWP etc, if my PIP payments were stopped, I think this would stop me receiving the Severe Disability Premium on my ESA (as I get it now and still would meet the other criteria). So would my ESA Severe Disability Premium automatically resume when my PIP Review was finally completed by the DWP (if awarded PIP)?