A dispute is a formal record that something went wrong with an order and the two parties could not agree. It is not the same as messaging the other person, and it is not the same as a support ticket about your account.
Raising one does two things immediately: it stops the seller's payment from being released, and it puts the order in front of our team. Everything else follows from those two facts.
Please try the other party first. Most problems are a misunderstanding and are settled in the order chat within a day. A dispute is the step for when that has not worked.