Too long for payment

We provided a service to the restaurant chain 1860 in December and have sent numerous invoice copies and when trying to call on landline we cannot get a hold of anyone or cell phones just not answered when we eventually got hold of someone they say payment going in today and nothing two months later I am passed being pleasant this was time out my day and my services rendered basically for free and with this money I have invoiced was money for my sons school stationery as being self employed budgets are tight and now 1860 joburg Restaurant chain has **** to me time and again now they just don't answer any correspondence or phone calls so basically if they did this to us what have they done to other contractors and we want his query answered with payment due to us for services rendered so that their electricity doesn't trip and they can continue making food.....but cannot pay us