Terrible service now lost car

In 2017 I took my car into Citroen to be fixed. I had a warranty on the car. They advised me the dealer to check the problem send everything so they can approve the payment. Next thing I'm told I needed to pay because they submitted 2 job cards for 1 repair that it was in..The warranty didn't want to pay the other one as they failed to identify the initial problem with the car. I have been seeking legal advise on this matter since then but legal aid has been hard to get hold of after I submitted everything. I decided to go there only to find a different car dealer there and they said they moved to Northcliff, before going there I decided to call. I was told they don't have the car I must go back to where I initially went. The last time I saw my car they were waiting for a car part. I'm not sure if it was ever fixed or where the car is as I was never contacted or anything further more. I'm not willing to pay anything as my warranty was going to cover everything if they had done the right thing.