So I need to top up my credit for the next month. ...

So I need to top up my credit for the next month. I had incredibly frustrating experience try to pay on-line with my master card debit card. So I tried calling them from my phone; but the calls were not getting through; last resort I tried contacting via twitter; I initially had a response, but now nothing.. there is no why no for me top up my sim.. I will have to leave this provider.