non payment

I submitted a two invoices 1st invoice was submitted on 2015/06/25 and the second on 16/10/2015 I've asked my assistant to follow up and she was been promised that the invoice will be paid the following week up to date its still is the same story today I spoke to the gentleman by the name of Sohil he tell me the same next week story, now this thing its been going week after week, cause this past Monday they told us we will be paid on Thursday 19/11/2015 invoice numbers are as follows 1st Invoice ***1 second Invoice 151001. why cant they tell us what's wrong instead of telling us to fix. each invoice cost aboutR1075 x 2 =R2150 my company name its Dikarabo RMS installations,