Credit limit increased

My Truworths account has been in arrears for a few months, due the economy being unstable. I have paid Truworths in full actually extra. I have asked the lady that called me to find out when am I going to make payment that it was paid. I requested from her a PAID UP LETTER which has not been sent to me. Instead Truworths increased my credit limit. My credit score has been humiliated by this account which is going to take a long time to get to be a good score. My question is.... Why increase a credit limit of a person credit limit when they miss a payment you call and insult them if the payment is late???? A valid answer will be highly appreciated.