I've been in a similar situation, so be aware of your rights.
1) If the car has a significant fault within the first 30 days you can reject the car outright, you do not have to accept a repair or a replacement, you can have a full refund
2) If you have had the car between 30 days and 6 months, you have to give the dealer one attempt to fix the car.
Point 1 is critical, but at the moment you are still covered. Of course it's better to have the dealer on side and talk through your options with them, don't shout and rant try to be reasonable faults happen, but also you only have so much patients, if they have no clue as to the cause then you should be looking at either a replacement or walking away, if a replacement then you will have to discuss temp car and who provides it.
Also, and I can't stress this enough as mine went south quickly, make sure you follow up all coversations with an Email confirming what was said, or make sure the dealer summarises what you have discussed in an email, this includes any conversations re specifications, quotes and finance quotes with any further discounts they may offer.
The dealer I dealt with used the same quote number to give me 3 options, so the only one saved was the last one they gave, this caused me lots of problems when they turned around and starting with the lies to cover their backs.
I really hope it gets sorted soon for you.
