I had credit cards and used all of them, back then I had no intention to pay the amount due but it's a burden on me and I wanna clear all my dues in this Dounia, so after few months of non payments all my accounts went to a collections agency, so is it permissible to negotiate the amount due on the credit cards to a certain percentage because the actual amount is high and people told me that I can negotiate with the collection agency to pay only part of the money that I've used to clear my account and establish new credit, so my question is can I negotiate with them not to pay the full amount knowing that I did use all the money and in my heart I know that am suppose to pay the full amount, but I do wanna know what you have to say regarding this matter cause lot of brothers had the same problem or still having the same problem and some of them did negotiate the amount due and pay only part of it, so please help us with your knowledge to clear this matter for all of us.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

al-Bukhari reported, that the Prophet said, "Whoever takes the money of the people with the intention of repaying it, Allah will repay it on his behalf, and whoever takes it in order to spoil it, then Allah will spoil him".
So, the person must pay back what he has borrowed. The Prophet (Sallallahu Alaihi wa Sallam) said: "The reward (due on the indebted) of a loan is settlement and thankfulness" [ Ahmad ].
It is also unlawful for the person who can pay back to procrastinate in paying as the Prophet (Sallallahu Alaihi wa Sallam) said: "Procrastination (delay) in repaying debts by a wealthy person is injustice" . [ al-Bukhari ].
So, you should pay back all that you have taken as a loan unless the loan was with interest. In this case, you should first repent to Allah from this forbidden act which is to participate in a Riba contract. The Prophet (Sallallahu Alaihi wa Sallam) said: "Allah has Cursed the one who consumes Riba (usury/interest), the one who gives it to others, the one who writes its deed down and those who witness it. He said: All of them are equal in sin" [Reported by Imam Muslim ].
Second, you should pay back the capital. As for the interest he has no right on it. Allah Says (interpretation of meaning): {… but if you repent, you shall have your capital sums. Deal not unjustly (by asking more than your capital sums), and you shall not be dealt with unjustly (by receiving less than your capital sums).} [2: 279].
We tell the inquirer to do his best to have the interest dropped and to pay back the remaining capital to its owner, except any part which he may forgive.
Also, we tell him to stay away from Riba contracts and never get involved in them again as Riba is among the major sins.
Allah knows best.