It was communicated via email.

We asked for a payment before f 8879 were signed and told TP to email payment confirmation along with executed f8879.  Only signed f8879 were emailed but we did not receive payment nor its confirmation.  We sent a chaser via email.  Only at the third email we informed TP that we need the payment to be settled in order to proceed with the e-file.  

It seems likely that the payment is not forthcoming as 3 emails were already sent out and no response received whatsoever.  Furthermore, the 2018 return was very late with penalties and interest.