Paid but refused to book our Flight

Be careful with Fastjet, I will not recommend this airline. I bought a ticket for mom via their website. I opted for eft payment method, the transaction went through from my bank account but they insisted they didn't receive it. I send them a proof of payment but they are now ignoring my massages. I do not know what to do my mom is sick and needs this flight to attend her medical procedure. They just took my money and we are left stranded and no one cares to assist us from their side. I am very upset, this airline is taking people for granted.