Bad service

I booked in my car for oil leak check on the 21st of May 2021 ....I was advised by my service manager Ms Linda whom advised that a certain part has been ordered from Germany and expected arrival date is the 7th of June 2021. I agreed to that and left the car with them and on the 8th of June 2021 after there was no call I went to the workshop to check if my car is ready only to find that they don’t even know where the part is ....or if the part in on airfreight or sea freight or postage or email or somewhere .....as Iam writing this review they still have my car with them And I wasn’t even offered a courtesy car since Iam inconvenienced. Where is the part ordered ? And can I have my car back. Car details : Mercedes Benz SLk 55...reg no: CR80SXGP