GeorgeMog, I'd love to be able to
help but I can't believe you've left it this long to kick up a fuss. Nobody seems to have appreciated that this Pioneer issue was a significant
problem, in terms of the OEM spec of a vehicle you may have/want to sell in the future and in terms of the lack of integration of the replacement unit.
I've been fortunate, or maybe (and I really think this is a possibility) my dealer has sussed my approach to this issue from the beginning and delayed delivery of my car until I got the RNS-E and nothing to complain about. In your case I think you need now to stop pandering to Seat and get the solution you want and paid for.
Unfortunately I don't think you can reject the car because a) its past the reasonable period within which you can do so (can you confirm the exact length of time you have had the car?) and b) because you have allowed Seat to attempt to repair the problems you are having.
Nonetheless, I do think you have a strong period to claim against the dealer to bring the car to the spec you ordered and carry out what ever works necessary to resolve other problems within a reasonable period of time - for a new car that time is not going to be greater than 14 days in my humble and unlearned opinion.
I'd be telling my DEALER - not SEAT UK (you are not their customer) that I want the fitted unit replaced with a fully functional unit (RNS-E) or that you will be replacing at your own cost and pursuing them for the cost of the replacement plus the loss of use etc etc. Put it in writing - don't do it on the phone. You can copy SEAT UK into this letter, as it may oil the wheels, but be in no doubt that your contract is with the dealer and if you financed / paid by credit card jointly with that organisation (to whom you should also copy all letters).
Just to reinforce what I have said ... you may get a result by talking nicely to SEAT UK ... you may however not. Writing insistently to the dealer laying out the facts (the unit is not as specified, does not work correctly, and is not a comparable replacement to the unit originally PROMISED (contractually - look at the
brochure) and specifying what remedy (what you want done - new RNS-E fitted) and within what timeframe (14 days) will get you a result, especially if you point out that you will not cease to exhaust your legal options in order to obtain a satisfactory result.
Lastly ... if SEAT UK are so certain that the RNS-E is not available, you should ask them how I navigated to Yorkshire from London this evening in my new Exeo ST (delivered Wednesday direct from Dealer) without the use of any equipment made by Panasonic. (OK I knew the way but I did use a factory fitted device that looks rather like an RNS-E, complete with crappy iPod integration!)