Hi SDMR
To process your payment today you could do one of two things, change the member number to all 9's and hope the super company match it with all other details there or pay everyone but the one person causuing the problem.
I had this happen to an employee with AMP and I had to do a search via the ATO portal for the correct member number and USI, so you could also try that first.
if no luck and details are correct I would suggest the first option whilst you sort out the employees number, which may have changed, or myobpaysuper get back to you. I don't think you will have any luck ringing the actual super company as they can be very unhelpful due to privacy laws and it may be bst for the employee to ring their super company and verify their member number is correct and maybe if both numbers and letters are required.