The blunt fact is that by and large they didn't help Haiti. The IMF and World Bank do not make gifts, they make loans which means they extract interest which has to be paid in dollars. That in turn means that the country getting the loan has to obtain foreign currency to pay back the interest.
One way they do that is by exporting to chosen countries but the way the IMF and World Bank works is that there are what are called "conditionalities". That means, amongst other things, that the country receiving the loan is obliged to buy certain goods from certain countries, whether or not they can produce them cheaply in their own country.
Since the country getting the loan has no choice in the matter, they flood their own markets with imports dictated by the IMF and WB, putting people out of work and destroying their own industrial infrastructure. As a result, these loan states become client states of economies such as the US (which controls both the IMF and the WB).
One of the reasons the rice industry in Haiti collapsed was because in exchange for loans, Haiti had to accept dumped rice from the US. That's what led to almost three million people flooding into the slums of Haiti - they were driven off the land by the economic vandalism from the IMF and WB.
One easy way to help Haiti would be to write off the debts - not just rescheduling them with interest penalties, but actually cancelling them, interest and all. Despite the publicity about states helping Haiti, nothing of the kind has really happened. It has just been turned into a sweatshop client state for the US to use. All very sad, but the reality behind all the spin.