My boss is not paying me back my money.

I am man from Mtandire, Lilongwe. I have been working with Pentecost FM since 2015 as a Security Guard. In 2016 I and my co-workers were promised a pay hike but months went by without the hike. We were then asked to submit the contracts we signed, but nothing happened still. When we asked for our contracts back, all my colleagues were given their contracts except me. From January to March 2017, I didn’t get my pay. When I approached the officials responsible, they just said they’ll pay me. Having worked 3 months without being paid, I submitted my resignation letter by the end of March. When I did that I was paid my March salary, however the January and February salary has not been paid yet. I have been going there to claim my 2 months’ pay, but they keep on saying come again.