There are a number of potential problems that could arise if government services are privatized. The two most important of these potential problems include:
Reduction in pay for workers or outright loss of jobs. One of the main points of privatization is that it is supposed to save money. One way that private companies can do this is by doing the same amount of work, but lowering the cost of doing that work. The costs can be lowered by making workers work harder (therefore letting some of them go) or by reducing their pay. This can be a problem for the workers, though many would say that it is a good thing because it saves money for taxpayers.
Less control of the work that is done. When work is done by government employees, the government can control them closely. The work will then be done in the way that the government wants it done. If private companies do the work, they may not do it the way the government wants. This can cause problems because government represents the will of the people and the people would no longer be able to express their will. For example, parks are something that people want to have and enjoy. If a private company does not keep the parks up the way the people want, it will be harder for the people to complain and get anything changed. The company will already have its contract and might not care about levels of popular satisfaction.