Chief Executive Officer John Donahoe boosted marketing spending by 29 percent in the third quarter and upgraded EBay's technology, aiming to lure consumers back to a company whose stock is little changed from March 2008, when he took the helm from Meg Whitman. EBay is also getting a lift as PayPal steps up its challenge to traditional payment systems by signing up more shoppers, who are using it more often and for larger purchases.