The reason they are having such a hard time is, they are using the same failed techniques they used on the Ixtoc I oil spill that happened in 1979.

http://en.wikipedia.org/wiki/Ixtoc_I_oil_spill

While technology for deep drilling has advanced greatly sense 1979, technology to deal with a potential disaster has not.

They were not able to stop the flow of oil from the Ixtoc I oil spill until relief wells were completed and the well capped on 23 March 1980, nearly 10 months later.