Waiting for payment for almost 2 weeks

I'm very unhappy how onair is doing business. I send 2 invoices for payment. Dates of invoice is 23 February and 28 February. I email invoice for payment. After some time the send me a email to let me know that my invoice must be made out to Comit Technologies t/a Onair tv. I did correct my invoices and email it back again. After another few days later the same person email me back saying the Onair tv vat no must also be on the invoice. Again I correct both invoices and email back again. Until to this date no payment is made and no feedback from them. In the past they told me payments are made very Mondays and normally the money shows 3 days later in our account. I send emails asking them when will payment will be done but no response from them.