JSN BMW service shockingly bad

They consistently make promises they don't keep! My car went in for service and I had to return it because it had a battery problem (a new battery was fitted during service). Whilst I understand that there can be problems but they say they will give feedback and they never do. I have had to follow up myself all the time and all I get is apologies after apologies for not fixing the problem and for not keeping me informed...I have given up...