Hi guys, Just need some advice, I received a letter from C.A.R.S Debt collection agency about a week ago saying that they were collectiong money that I owed to o2 to the sum of £420.04p, which is strange because i currently have an o2 contract that i pay monthly, so i just ignored this, then today I recieved a letter from them saying that they have come to a settle offer with the named client being o2 and that i should phone them to arrange a payment within 14 days so i was wondering if there was any kind of letter I could send them asking for proof of the debt? thanks