Dell nightmare service. It can't be more horrible.

It's been more than 2 weeks. Engineer visited 4 times, changed motherboard, battery, back cover, power jack & adapter. They want to come again to replace another battery not sure why? They made my home their laboratory. Still they don't want to replace. Someone called  & his supervisor , who initially register this case don't even bother to reply, though I drop them few mails. They don't even provide their escalation details. Dell support seems to be filled with bunch of irresponsible and useless team. Can at least one sensible person in the whole team who can provide good support and respond to this? What are my escalation options?