I am missing something when it comes to using the marketplace. I have seemed to make some bad purchases and nothing you can really do about it. Some guy just left his twitter account as ‘support’ lol
Love your work otherwise, i care more about graphics too 
I know that you can rate and leave comments on the marketplace package page, other than that you can email Epic and ask for a refund, though I’m not sure whether or not they’ll give you one.
If a content creator is refusing to support their product, contact epic at marketplace-support@unrealengine and they will look into it.
Actually right now (3rd of october 2015) all the comments to the marketplace assets have disappeared. Seems like Epic disabled the function to
rate and comment the packages.
Thats very bad, as those comments and questions there actually were the only source of feedback to the packs.
The packs have lots of issues and if you don’t have the chance to be aware of them before you think of buying, then i would not recommend buying them anymore.
That’s true, for more information take a look at this thread: https://forums.unrealengine/showthread.php?85905-What-happened-to-comments
Beside rating and commenting you could also post your opinion into their support thread -> most packages that you can find on the marketplace has one
According to Chance on the stream, it seems to be a bug rather than intentional removal. It should be up fairly soon. =)