<prompt> Human: I am a fairly recent freelancer. I dont do it enough to charge HST yet. I charge clients based on the labour and equipment and do not include taxes. I recently did freelance work for a college. I did not sign anything with them-- I just gave them an invoice for the work I did. They deducted some amount, I received 694.50 instead of 800 with no explanation or pay stub. I want to say something but Im also not sure if Im just not used to dealing with real institutions and not independent clients. Im in ON, Canada. Hope this is the right sub.Thanks!  <response>: After your payment period has elapsed send then a written past due notice for the difference. 