Citroen DS4 feb-23 engine fault repair needed and service light appeared

Feb-23 EML appeared and eco mode not working
2 days later had starting issues
OK for a week still EML
Then problem starting
New battery fitted (March)
Still EML
Driving and car goes into limp mode, RAC towed and told new injector required still EML
Took to local garage told battery connection incorrect EML went but came on next day. Fault stating BSI
Took to a diagnostic specialist found to be incorrect battery installed so put in start stop and disabled the automatic lights and wipers as this was showing as fault code. EML disappeared but came back, took back HD reprogrammed the computer said lights have gone, 3 days later EML back.
MOT due next mth and losing the will. Plus bill at £700