A seller will nearly always try and resolve a problem if given the chance. The leaving of negative feedbacks can cause defects on a sellers account which can lead to them losing their account.
Always contct a seller first before leaving feedback, that should be your last resort if the seller is not helpful.
There are many neutral / negative feedbacks here, so if you wish to change any of those to a positive, contact those sellers to send you a feedback revision to complete.
