wrong item sent

i ordered two items from hobbyking. a rc plane and a turnigy neckstrap...i got an email saying neckstrap was no longer in stock and would i like a store credit.they gave me credit and said plane was in stock and being shipped. a week later i get the neckstrap in the mail but no plane. hobbyking says plane was delivered according to tracking. i sent a pic of box and neckstrap to them.now i cant get any response from them. been over a week.