same here i pay my ex every week with out fail and we write it in a book .
I got letter of csa other day saying i had to pay 1000 pounds in 7 days befor the 15th of may lol funny as i only got letter on the 25th june and date at top of letter was 23rd june FOOLS
i rung them up and said wtf is this letter and they said they had never sent a letter out to me ,so i said wtf is this in my hand ,they again said they had never sent letter out ha ha then they blamed a computer .then few days later i get letter saying i owe 80 pound
they also wanted proof of my wages i sent my wage slips off 4 weeks ago no reply back