Motorhead said:
Andy,
Just to pick up on your point about the (Porsche supplied?) battery. I thought that parts supplied and fitted by Porsche themselves are covered by a (2-year?) warranty? If it has a part number, a battery is a part..!
I'd certainly go above your Porche dealership and take the issue up with Porsche directly.
Good luck..!
Jeff
I agree with Jeff, irrelevant of whether the Warranty on the car covers the Batter, legally any item supplied needs to be ‘fit for purpose‘ and failing after 4 months would suggest it wasn’t. As the supplier of the battery Porsche should be required to confirm the reason for failure. This doesn’t appear to have been done. Normally a good supplier knows that cost to clarify the reason for failure is normally more than just replacing it so that is what they do! I think taking this at its most basic legal argument. You were supplied goods (battery) by a supplier (Porsche) and it would be reasonable to expect the goods to perform their designed function for a suitable period of time. 4 months would not in my opinion be a suitable period of time so the duty lies with the supplier to confirm the reason for failure so it can relinquish its duty of supplying another under their original contract to supply something which would function correctly for a suitable time in normal use.
Frim Citizens advice web page
[h2]You’re entitled to a repair, replacement or a discount[/h2] Make sure you return the item within 6 months of buying it 23 May 2018 . It’s easier in the first 6 months, as you won’t have to prove who caused the fault.
If the repair or replacement isn’t the same as what you bought, you’re entitled to a refund instead. You could ask for a discount instead, if you’d rather keep the item.
[h3]What to say[/h3]If you're confident the item's faulty, you can say something like this:
"Under the Consumer Rights Act 2015, goods should be of a satisfactory quality, fit for purpose and as described. My rights have been breached because the item you sold me is faulty. I would like a refund/repair/replacement."
If they say the problem’s your fault, it’s down to them to prove it. Tell them you know this - and ask how long it’ll take if they send it back to the manufacturer.
[h3]If you paid by debit or credit card[/h3]You may be able to get your money back through your bank if the seller’s refusing and you paid by debit or credit card.
Contact your bank and say you want to use the ‘chargeback’ scheme. Many bank staff don’t know about the scheme, so you may need to talk to a manager.
If you paid by credit card and the item cost more than £100, it may be easier to tell your bank you want to ‘make a section 75 claim’. It’s another way to get your money back.
[h3]If you’re still not getting anywhere[/h3]Take the following steps:
[ol][*]Use our
complaint letter for faulty goods- it contains legal terminology and may help the seller understand that you know your rights.[*]Check if the seller’s a member of a trade association. Look on their website or ask them if you can’t see anything. Contact the trade association, explain the situation and see if they can advise you.[*]Ask the seller if they’re a member of an
alternative dispute resolution (ADR) scheme - it’s a way of solving disagreements without going to court. A third party will mediate to try and reach a solution.[*]If they don’t respond, they’re not a member of an ADR scheme or won’t use ADR, keep a record of the fact that you asked them (and the date). You’ll need this if you end up in court.[*]
Choose an ADR scheme yourself to try and solve the problem more informally. It’ll help you later if you end up going to court.[*]
Take your case to a small claims court (or
use the simple procedure if you’re in Scotland). This is a last resort and can be expensive and time-consuming. You should only do this if the item was particularly expensive and you don’t mind the stress and time of going to court.[/ol]
https://www.citizensadvice.org.uk/consumer/somethings-gone-wrong-with-a-purchase/return-faulty-goods/
]. 
