SMS threats or ********

I receive SMS messages from AMPATH threatening legal action if I do not pay accounts. They have not sent me invoices but happy to threaten me via SMS. Typical of ********. Are these ********? I tried calling them 3 times and their exchanges are overloaded. I wonder why? So I ended up sending them an e-mail. Last time they told us to ignore the message as it was paid when the invoice arrived. Are there high handed actions reflective of their attitude. If this is the case we need an alternative laboratory in this country. I will certainly be going elsewhere.