Car for repairs

I've had enough. Dropped my car off on the 7 November to get the engine refurbished and paid in full.The promised was two weeks. Fast forward to 8 December I go to collect my car and it was still sitting there,engine not even assembled. Their latest final promised was in 3days on 8 December. Its 20 December now ,I'm over the excuses.i need my car.i need to escalate this