Confusing letter from the CSA

I received a phone call out of the blue from the CSA last october, telling me they needed to speak to me, and could I confirm some information over the phone. I refused, as I didnt believe it was the CSA, so they agreed to send a letter. The letter said to contact them, so I emailed via the email address on the CSA website.

A little while later, a get a payment into my bank account and a few days later I get a letter telling me my ex has been told to pay £5 a week, backdated almost a year.

Seeing as I hadn''t contacted the CSA at all, it was surprising! Ex has payed £10 fortnightly ever since then, never had a problem.

Now, almost a year later I get a second letter telling me they have JUST worked out that he needs to pay £5 a week, which will be payable fortnightly and the dates he needs to pay.

Underneath, it then says "This means that Mr XXX has been asked to pay too much child maintenace in the past. We will contact you again soon about what this means for your case"

However it says the number of payments, when it starts, when it ends, how much etc and any arrears or overpayments. Both arrears and over payments are £0.00.

If he has been paying what they said he should for almost year, without paying off arrears he apparently has (not sure how he has arrears tbh!) then how has he overpaid?

Do you reckon its just a mistake on the letter and it was just meant to be a yearly update on when and how much he should pay? Or am I suddenly going to be faced with repaying maintenace to my ex?!

Sounds typical CSA to be honest, They produce some ridiculous letters seemingly at random

I would phone the CSA and ask for clarification.