You might be able to get an extended warranty to pay for a slip yoke. Is it a Ford ESP contract? It's not a hard fix to remove the driveline, pull it apart, clean and lube the splines. Anti-seize works good as the lube.
This is obviously just an over the internet/unofficial non-sanctioned guess/half-arse'd diagnosis. I'm not positive that's what's wrong with it, but we do fix them from time to time.