Extending is a good idea.
Better: give feedback and rating.
If this is a lottery and not a work to get what is best for you, never mind my suggestion.

Thanks for your note Tatlin! Apologies i have been slow to respond as i've been at school all week (hence the extension). I will respond very shortly! Thanks for your patience.

I received an invite to this contest, although i already submitted some proposals.
Anyway, your lin to pinterest page DOES NOT work.

Update it or remove it form your brief.

Thank you for the feedback. I've had a round of review amongst my peers hence the reason for extending again. I will try to give more tangible feedback.