Condonation letter with regard to Form 108

I completed my articleship on 24th April 2018 but due to my severe health issues along with exams I could not get the form 108 signed on time.

Also due to non availability of my principal after exams I was not able to get them signed up to 23rd May 2018(Due date for submitting Form 108)

But today i.e 31st May 2018 my Principal signed the form but he is denying to sign the condonation letter.

Now what should I do ? Can anyone help please ? Will Institute accept my form 108 ? Will my medical certificate along with reports be adequate for the purpose?