2016 Citroen C4 ad blue pump failure

I had a Adblue pump problem, which was replaced, than the mot and service was due ,I picked up the car and started it and found it to running lumpy, so went back into the garage, and said about it ,told it was fine ,on the 3rd time the service manager, came out and we took the car for a run ,it was fine when it was moving .the service manager told me it was because the oil filter had been changed. So I thought ok .so 2 weeks later there was big puff of blue smoke, and the ad blue warning light ,came back on .so got in touch with the garage, it will cost other £553 to put right .I do feel the vehicle wasn't right ,when I picked it up .I have the Citroën care line, have phoned them at lest 5 times and get the same message, we will talk to the garage and get back to you in 5 working days .this has never happened. So I spoke to the garage, and the care line has never phoned them .so would like advice on where to go next please.