Being billed for a phone I don't have

I called CellC inorder to get a contract phone with them. I ordered the phone but the WRONG phone was delivered. I immediately sent it back without signing for it not did I open it. As time passed; I get notified that CellC deducted money from my account so I called in. They didn't have the phone I wanted so instead of telling me; they send the wrong phone. Now I've been trying to get a refund for a month and also trying to cancel this stupid contract because I'm being billed for a phone I don't have but they keep giving me stories. I've been calling and calling and I keep getting these nonsensical responses from them. I've emailed the proof aswell but they're "still investigating". STAY AWAY FROM PHONE CONTRACTS WITH CELLC