Placing 300 Character Limitation On Reply Tickets

[SupportCenter]

Using current version of helpdesk.

There is an restriction on our tickets that we only allow the buyer to place only 300 Character limitation. The problem is there is no limitation on the reply ticket. Buyers have been cutting and pasting all sorts of things that are annoying us. We would like to know how to place a restrictino of 300 character limitation on the reply.

Also would like to know how to place this restriction on all documentation send by the buyer in the ticket, if any exist. Thank you.