Cannot make online purchases all of a sudden

I've gone through the hoops of verification codes, clicking links sent by Dell to my phone and even changed my password trying to use my credit line to make a purchase.  I've called Customer Service who advise me to call Sales who advise me to call Customer Service.  The latest rep saw nothing unusual (no hacking) on my account.  I can access my info and everything looks fine except I can't make a purchase.  This is outrageous.  On the positive side, the same item I've tried to buy from Dell for the last couple of days is available for the same price on Amazon and I just purchased it.  Not going to continue doing business with Dell if they can't fix these types of problems immediately.