Lack of payment after services rendered

At the very beginning of February I, my catering company, did a catering for the Matatiele Local Municipality. The job was a breakfast and lunch for two days. After the job was completed, I then handed in the invoice for the job, but up to now the payment has not been made. <br> I have been to the department responsible to find out the reason and every time I am told......\next Friday the money will be in your account". That was three weeks ago.<br> Please assist"""