not happy at all

Good Morning

on the 26th February I called munnik bassoon dagama incl ********** 016 for a settlement to close my jet account. on the 27th they e mail me settlement amount was R3489.36 NB KINDLY NOTE THAT SHOULD THE AFORESAID SETTLEMENT NOT BE PAID IN FULL WITHIN THE NEXT 7 WORKING DAYS FURTHER INTEREST AND LEGAL FEES SHALL ACCRUE. 27 was on wed 28 Thursday 1 Friday 2 Saturday,3 Sunday not working days on the 4th Monday I paid at lakeside mall jet full amount it was within 3 working days I called on Tuesday requesting my paid up letter the guy was very rude his attitude telling me that I am still owing them R1053 my payment was very late ,how so I really don't know according to my understanding I'm early I paid before . im really confused if it was a false advertising must I still trust them when they call me