Partial payment refund is possible when the order is not completed or the delivery terms are not followed. In most of cases, Overgear arbitrage solves partially delivered orders.
But you can solve the problems with the seller directly so they can complete all agreed terms unless you do not confirm the delivery and they do not receive the payment.
Partially completed orders
The cases of partially completed orders are:
30% or more of work was completed
the seller has reasonable issues why the order cannot be finished
the order was completed but the terms were not fully followed
late item/service delivery date
Partially delivered orders cannot be the case for Titles and Achievements that are limited by time (it will be impossible to obtain them after a specific period of time), for example Gladiator, Hero of Alliance or Horde. If the seller accepts such order but he lacks 1 rating point to get the title, the order is considered failed.
How to request a partial refund
If you could not solve the issue with the seller directly, contact arbitrage. Proceed on the «My orders» tab and choose the order you have problems with, then press «Contact arbitrage».