Fiesta Driveshaft Warranty

Hi, first post on here so apologies if it's in the wrong place...

I need some advice/reassurance regarding the driveshaft on a Fiesta and if it is covered by the warranty?

I took my car for it's first service not too long ago at Evans Halshaw and they informed me that the driveshaft needed replacing but they weren't covered to do it under the warranty and should contact the dealer I bought the car from. After weeks of chasing I've got the car booked in to be inspected next monday at the dealer I bought it from, but they still wouldn't confirm whether this would be covered by the warranty, and is instead based on the decision of whoever looks at and carries out the work on the day??

Now I know that this is a very common known fault with these cars, a fault which Ford is well aware of and have been reassured by a colleague that they know quite a number of others who have had the same issue and successfully had it replaced free of charge under the warranty, yet anyone at Ford I have spoken to is still so reluctant to agree to this.

Is this just a case of them knowing the repair is covered by my warranty and just trying it on to see if we will pay before giving up and agreeing, or is it genuinely down to the person on the day and it may not be covered at all?

Thanks,

Ryan