Considering the LG G3 as your next smartphone? Good on you; it’s an awesome device! If you’re thinking of purchasing the handset through T-Mobile you’re in luck. A limited-time promotion sees customers picking up a cool $100 mail-in rebate Visa card when pairing the LG G3 with The Un-carrier. The deal, which started on November 19, runs through December 14, requires buyers postmark the rebate form by mid-January.