Harassment even after subscription has been paid!

This is possibly the worst company to deal with. You pay your subscription via EFT because their payment links don't work and then for days on end, they harass you stating that you haven't paid. I sent the proof of payment to numerous people, bearing in mind that the EFT was an immediate payment. The "manager" called me on Saturday evening assuring me that it was all resolved just to be harassed again the next day and the following day. I am seriously frustrated with the *********** PEOPLE who are unable to do their jobs. With all of this in mind, you can't get hold of them on the phone, they ignore ALL my WhatsApp messages and don't respond to a single email, so how am I meant to get this resolved?