You probably have a copy of their "terms & conditions of sale" in fine print or a very light colored print on the reverse side of the invoice you received when your PC was delivered.  This will have some very basic return & replacement info outlined on it.

I've just done a search on their website here in Australia & found at the bottom of this page & all others is a link to "terms of sale" so I guess wherever you are there will be a similar link.

HOWEVER . . .

DELL will only have terms that favor themselves & it sounds like you should be consulting your local version of our "FAIR TRADE ACT" because it sounds like you have been sold something that was not fit for the purpose it was intended & you not only may be legally entitled to a replacement but compensation or upgrade.

Personally I'd have demanded major replacement of the whole PC after the 3rd time it had gone in for the same part to be replaced, you must have an awful lot of patience.

You should NOT HAVE TO PAY to upgrade

Get advice from your local government trading laws - DELL will have to comply with them - not make you bend to their ways

GOOD LUCK

I have a Dell labtop that needed more upgrading in memory and so I was "advised " to purchase two 1GB memory gaming chips.  I then talked to someone when I received them and they told me how to install them. (I had seen the video also earlier) I did what they told me and put both the chips in the back of the labtop, one saying that a ddr2 chip should go there (so I installed the ddr2 chip there), the other one said mma2 and I asked the instructor at Dell support are you sure I should put the other chip there and he said yes.  Then my labtop would not go past the welcome screen after I signed on . Now they say my mother board has gone bad.  It was fine before you guys told me how to install these chips and I am not going to buy a new mother board when it was fine before I was told to order and install the chips.  Dell sent me a shipping box, paid the shipping charge to be repaired.  I do not expect to have to pay anything because I also had recently purchased an extension warranty for 2 more years and any cost should be on them. Hope I do not have multiple mother board problems also. Labtop was running slow and so that is why I wanted to upgrade the memory in it. More information to come on this when it is repaired and returned to me.