What is a credit adjustment mean when you swop phones?

[denzilsam22]

My two children stopped their mobile phones on our sky account. When we got notification of the completed swap an email from sky showed a £22 adjustment and a £50 adjustment on each phone yet when we paid our monthly bill there was no credit adjustment like that. Ended up that the account with the £22 adjustment owed Sky £15 and the £50 adjustment was owed £9. Crazy 

[caesarome]

Do you mean your children swapped their phones for other models, if so the credit adjustment might be because there was still an amount on each one that needed to be paid.

[denzilsam22]

We understood that there would be a payment of £15 needed for my sons and £9 owed to my daughter from Sky when the swop was done. Yet we received two emails that stated that a credit adjustment of £22 on my sons and £50 on our daughters would be put on our account. As it's 0% credit cost and the phones were judged to be better than initially quoted for and worth more I don't know what Sky are playing at ?