It's quite surprising, that your reader comes without the play store. Onyx did release firmware package without google apps a couple of times, but not 1.8.2 as far as I remember. Please excuse me for double-checking it, but are you sure there's no play store in the list of the apps: home screen - application - play store? But I assume you have double-checked it already
First of all, could you please verify the model name: it's printed on the backside of the reader and can be found in the settings: home screen - menu - settings - about - about device - model number
Get the latest update for your reader from
http://120.76.193.63/index.php/en/support/firmware, download update.zip and copy it into the reader. I usually take external sd-card away just in case, and use the root folder of the internal memory: \sdcard\update.zip. You don't need to unpack the file. Detach the reader from the computer. Finally go to home screen - settings - about - system update - check from local storage
I hope these steps will help you solve the issue. Please don't hesitate to ask here if you have any other questions. You could also try contacting the customer service:
sales@onyx-international.com