Time Freight - Late and want to charge additional

I received a quote from Time freight which i was happy with and phoned them to arrange payment, I paid the quoted R736.60 and then asked for POP which they were unable to send me, after waiting 16 mins with their customer service i was advised the delivery would happen on Tuesday, I arranged for some one to be home all day Tuesday to accept delivery. Later that afternoon i spent a total of 42mins on hold (and various times they hung up) only to be told that the delivery would take place on the Wednesday.<br> <br> After explain all of this i asked for a discount as i paid for a service and have not received it, I woke today to see an email stating that i am receiving a 20% discount but now owe them an additional R195.08 - I am unsure why and they wont deliver with out me making the additional payment.