PAYFAST - but beware, you may pay twice

So I receive a bill from LANCET for an amount owing - and as per suggestion a link to PAYFAST. Start completing and am advised "an error occurred and transaction could not be completed". That being said I went on to my ***X banking app - LANCET an accredited beneficiary - and paid the bill. Do I not just receive a mail today telling me - from PAYFAST - that the issue they had has been rectified and they have processed the amount. True as nuts - an unauthorised debit to my bank account. Email goes further to tell me to furnish bank details fora refund - to a bank account they actually debited. Never heard of that in my life - if you can DR - you can CR. I was advised they do not keep bank account records(???) and are unable to refund without this information. So- they took my money without authorisation and now I have to request it back ...... from a PAYFAST !!!There is something not right and seems a good way to increase your bank balance until someone asks for their money back. Never to even try and use this service.