Dell Warranty Issues

This post is more to see if other people have has similar issues with Dell.
Since 2007 I have been a customer with Dell after buying a laptop on eBay and I have to say when Dell products work they tend to work well but when they fail Dell service and warranty seem to fail even more. So after three replacement laptops (Alienware laptops) I have found myself once again having issues with the laptop and Dell.
It was January when contact was initiated by myself regarding issues with a wifi card that has been replaced and working successfully. Shortly after that I noticed overheating issues on the laptop and again another service engineer was sent out to replace the fans, heat sink and motherboard three times. Unfortunately after repair I notices the screen started flickering and reduced brightness even with the brightness level set to max. This is where Dell advised another service call was issued, only a few days later they decided no to honor their word or warranty and decide to only offer me the service of sending away the computer to their service depot for testing. I advised Dell Executive Advanced Resolution Group that I used this service before with a previous laptop and it failed to rectify the issue. They stood firm on this and now I have had my solicitor contact Dell on my behalf. I have retained all the emails from Dell and also have a recorded call with the employee saying they wont honor the next business day warranty even if its paid for!
I was advised that replacement parts are new but that cant be true when refurbished stickers are on the parts. Refusal to talk to supervisors by customer service representatives. Obvious tactics to get you to hang up and forget about it. Not honoring warranty status. Advance resolution group who wont reply to emails. Tell you a part is out of stock and the replacement with be another, but wont tell you what the replacement is.
This issue has been going on since January and my solicitor got a similar response to what I get in that the system must be sent away for testing, but why would I pay for next business day onsite warranty if this is my only option.
The graphics card and wiring has not been changes and in the recorded call the employee states everything possible was changed and that sending the laptop to the service depot is the only option available to me. It is the graphics card that is/was (not sure which is correct) out of stock.
Has anyone else received shockingly bad service and a lack of consumer rights from Dell? and if so has the issue been resolved?