Pip assessment cancelled by assessment centre but

New appointment letter just arrived and it says this is my second and last appointment for assessment and if I do not attend my claim will be cancelled. My husband spoke to the assessment centre when they phoned to cancel assessment which was at 1pm, they phoned at 1030 saying hcp called in sick and assured my husband this would not count against us as they were cancelling,
I read advise to report it to DWP decision maker, would this be sending letter with info to the same address PIP form was sent? Sorry to bother you just brain in melt down, again,
Thank you
Linda

Due to disabilities I cannot use the phone and husband works in basically a big metal box so cannot contact him and just searched, cannot find phone number. I have typed a letter to send, will send tomorrow with proof of delivery. I always expect worse case scenario and anything could happen. Of course extra worry is if they cancel again will my file be returned to dwp, pip application stopped and DLA stopped too? Sigh... I panic over nothing, give me something to panic about: Meltdown.