There is no such thing as fate... is only karma. And yes, karma
can be changed, if you think you have done something wrong, you can
repent, do virtuous deeds, etc, and this will help overcome the
karma. Chanting also helps...
In the Mahayana tradition... it is actually possible to pray to the
Buddhas and bodhisattvas for help. I'll summarise a little on what
my dharma teacher said about this. This is called Skillful Means,
and the Buddhas and Bodhisattvas is able to help in certain cases.
It really depends on your situation... and what you pray for must
be of right intentions, what you pray for must not contradict the
dharma. For example if you pray to win big bucks from toto or
gambling then of course you won't find that praying is helpful.
Instead, the more you pray, the more you won't win. If say you are
in financial crisis and you have a family to feed.. you really need
money, and if you chant Namo Guan Shi Yin Pu Sa very often, very
regularly, and pray for changes.. then you might indeed see a
change of events.
However, it may not work in all cases. Because still it is your
karma. The Buddhas/bodhisattvas can only help you have 'access' to
these wholesome, virtuous seeds. So let's say you have $100 in your
bank, if you are in crisis and you need some money, you pray to the
Buddhas/bodhisattvas you may get some money from your bank (i.e the
8th consciousness, alaya consciousness). But if the money is used
up (i.e the karma is used up) then even if you pray to
Buddha/bodhisattva, they cannot help you.
So if you really didn't see much changes then perhaps it is because
you do not have enough good karma. So it is important also, to be
wholesome, do virtuous things, avoid unwholesome
actions/speech/thoughts, this is to accumulate blessings. But that
is not enough of course... because there is a saying by Buddha in
accordance to a true story.. if you cultivate blessings and not
wisdom, you will be reborn as a royal elephant (good karma but
ignorant), and if you cultivate wisdom only but not blessings, even
after you become Arhat (liberated person who attained Nirvana), the
lay people do not give you alms to eat. So, meaning even if you are
enlightened, on the material side you are poor.
But.. still for one who has wisdom, he completely every moment as
it is, irregardless of the life situation around him. He is
unaffected.. peaceful.. calm.. and joyful at all times. Therefore
dharma practise is important, it allows us to be liberated and at
peace, happy at all times.
p.s what kind of "fate" do you want to be changed? 
