Got burned by the Arbiter

I lost the first few tries at arbiter, and my friend gave me fragments to run it again with him. We only got two tries on the second round of trying before we got kicked out of the instance. So then I had to buy more fragments again, and we fought him a third time. I died, and he didn't, but he couldn't pick up the loot that was dropped. I had to click respawn at checkpoint, and all of the loot disappeared, and the item that I needed was laying on the ground and I didn't get it. I just lost a multiple divine investment, and I don't have hardly any currency. So the attempts and effort put into being able to do the main endgame activity and fight the pinnacle feels empty and like a waste of my time and it's a really bad deal. All of that investment to get what I wanted and worked for, just to see it and lose it due to a bug. I don't think there's anything you can do for me, but if there is a way to keep future players from this issue I hope it can be avoided.

(Their response)
Hi there,

Thank you for the message and I am sorry to hear about this issue. Unfortunately we are not currently offering email Technical Support, due to limited staff resources. We apologise for any inconvenience this may cause.

The development team have provided the following resource to help with troubleshooting technical issues: https://www.pathofexile.com/forum/view-thread/3072628