CAPE TOWN, Oct 28 (Reuters) - South Africa plans to freeze public-sector wages for the next three years to help cut its salary bill and contain a yawning budget deficit. The proposal raises the risk of widespread strikes by the 1.3 million-strong public-sector workforce. Here is why the government wage bill is a problem. WHAT IS THE PUBLIC WAGE BILL? South Africa spends around a third of its budget on the salaries of its civil servants, including national and provincial officials, doctors, teachers and police. In the fiscal year that started in April, the government projects it will spend around 639 billion rand ($39.54 billion) on their wages.