Sunderland narrowly escaped relegation last season but only £13m has been spent on new signings Sebastian Coates, Jeremain Lens and Younes Kaboul, while striker Connor Wickham has been sold to Crystal Palace for £7m.
The Black Cats have picked up just one point from their opening three games and already looked destined for another relegation battle.
“I’m not happy at all. Every day is a different story,” said Advocaat, who was persuaded to stay at the club this summer despite initial retirement plans.
“I wasn’t intending to say this but I will say it because I don’t care.
“If you have the right people in place, and I think they are now here, and you have some resources to do something, I would do it differently, let’s say it that way.
“Lee Congerton (the club’s sporting director) is doing a great job with little money. We really appreciate that but we need more. We really need two or three players.
“Last year we were lucky to stay up, with a lot of commitment and energy,
“Everyone was in the right shape and it made them better than they are. They did really well so for me, you will never get a bad word about that squad. But we can only improve if we get some other players in.”