Akon is up to his neck in $51,000 of construction bills on his Georgia mansion ...

and he still hasn't paid up -- this according to a new lawsuit filed by a local contracting company.
Southern Electric filed the lawsuit against Akon in Georgia Superior Court, claiming it completed over $344,000 of work on Akon’s place -- electric work, framing, molding -- but he refused to pay $51,941 on their final invoice.
According to the suit, Southern Electric contacted Akon’s mommy last November ... not just to tattle, but because his mother was acting as his agent in the deal ... but still, S.E. has not received a dime.
They’re now suing for breach of contract for the amount allegedly owed, plus interest.
Akon’s Georgia palace is a two-story four-bedroom, eight-bath model that he forked over 1.65-MILLION clams for.