haven't got 和don't have有什么不同

haven't got 和don't have有什么不同
如果说haven't got是现在完成时,那么下面句子里,We haven't got many tomatoes,哪个词代表有没有的含义呢?难道是got?
如果是现在完成时,请问这句话为什么要用完成时?用We don't have many tomatoes,
We haven't got many tomatoes这句话的时态到底是现在完成时还是一般现在时？
如果have got=have，如果have got就是一个动词词组，那么否定句就应该是don't have got，而不应该是haven't