South African miners are altering demands agreed upon by union officials and platinum mining companies last week, which could further delay a resolution to a 21-week strike that has crippled the country’s economy and affected much of the world’s platinum supply.

The Association of Mineworkers and Construction Union (AMCU) wrote to Lonmin (JSE:LON,) Anglo American Platinum (JSE:AMS) and Impala Platinum (JSE:IMP) on Monday, demanding an extra one-time payment of $270 per worker and an end to criminal charges against members, according to Business Day.

The Wall Street Journal reported that the union also demanded that 235 workers fired during the strike be rehired and there be a shortened timeline for the installment of wage rates, from five years to three.

Last week, the three platinum companies said they had reached an agreement “in principle” with the AMCU to end the strike.

More than 70,000 mine workers have been on strike for 21 weeks now, halting production of about 40 percent of the world’s platinum supply. It’s cost the companies about $2 billion and caused South Africa’s first economic contraction since 2009 last quarter.

At an address in Cape Town on Tuesday, President Jacob Zuma promised to boost the economy, improve the business climate and help resolve the “untenable” strike.

Standard and Poor’s cut the nation’s credit rating to one level above junk last week on fears that slow growth will make it hard for the government to hit its budget targets.   Fitch Ratings downgraded its economic growth forecasts for South Africa in 2014 down to 1.7 percent from a previous estimate of 2.8 percent, but maintained its rating at BBB, the second-lowest investment grade.