Epiphone DR500 MCE problem

[bluzerman]

Hello , i have bought a brand new Epiphone Masterbilt DR500 MCE VS guitar and have a problem with it , it has 2 pickups, one undersaddle piezo-type and one ceramic soundhole, they can run in mono with possible blending both of them together or stereo with 2 separate outputs for each pickup. Soundhole pickup works good , no problems with it but the main undersadle pickup is making heavy feedback .
Feedback is quick and it comes up no matter the volume , as soon as volume is even a little up it starts feedback, i tried blending it together with soundhole pickup but when i blend even a little on the piezo side it starts feedback, i tried conecting it to separate outputs( stereo) and its same , eq dont help , changed cables , 3 different PA's , different rooms , even put that rubber feedback buster but nothing helps , i cant use the pickup at all , there is no pickup hum from the guitar when im not playing , its just feedback as soon as i touch the strings , even when i can get a little tone from that pickup on the lowest volume it creates some strange muddy , boomy tone when i play a certain notes on the 3rd and 4th strings.
I am not good guitar tech so if anyone here knows does it have to be big problem or can it be some silly little problem , bad soldering or something that can be easily fixed?
Reason i ask this is because i bought it on THOMAN music store , Germany , i bought it online ,and i live in Bosnia and Hercegovina so i can not just go to their store and fix it , i have to send it , deal with customs procedure , not to mention waiting time coz its my only working tool ,and right now i dont have one...and btw i wrote to them last week and still got no answer ,so i should even consider being ..well ..cheated i guess..and fix the thing myself if possible. Thanks for any help.